GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: PCPhack on January 27, 2018, 04:14:00 PM
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About to begin a bottled Marauder .25 build. I may convert it to a .30 or other caliber later, depending on how my slug testing with the .25 ends up.
I have on order a 4500 psi carbon fiber tank, WAR 3K Marauder regulator/tank block, and RAI R016 modular Marauder chassis. As I want to fill the tank to 4500, and regulate down to 3000, I will use a burst disc to protect the Marauder in case of regulator failure. However, I would still feel more comfortable to upgrade the 3 valve screws. Does someone have a known good source for these? I looked at Magnum Airpower, but the heads on theirs look too flat.
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The MRod uses completely different valve screws than the Disco.... The MRod screws are 10-32, conventional full height heads, and are set down into the valve to move the shear plane up into the head of the screw.... I am not aware of better quality screws, but if you want the best you can get, I would buy "HoloKrome" brand, as they have the highest UTS I have seen for alloy SHCSs (200Ksi).... I believe that the weakest point in the system would be the screw heads plowing through the tube because the sear slot is close to the bottom valve screw, and that should be the point of initial failure (if an O-ring doesn't pop first, which it may).... The next burst disc above 3K is 5K (sometimes in England you can get 4.5K).... and if you want to use a regulator setpoint of 3K, that is what you will have to use.... because 3K burst discs will not stand continual use at 3,000 psi (I have seen them fail at 2,500).... Therefore you effectively won't have any protection from the burst disc, and if the regulator fails/bypasses you will end up with tank pressure in your MRod....
Having said that, there is a difference between the MSWP of 3,000 psi (repeated cycling to that pressure) and a one-time overpressure to 4,500 because of a regulator failure.... Providing Crosman did their homework, and followed a typical guideline for pressure vessels of a 3:1 safety margin above the MSWP.... the reservoir should be capable of withstanding 9,000 psi without failure.... That is still twice your "oops" pressure from a regulator failure.... Should that ever happen, after releasing the pressure you should inspect the gun for any signs of potential overloading, paying particular attention to the area of the tube behind the valve screws.... looking for any sign of distortion or bulging of the tube in that area.... If you find none, then I would replace the valve screws with brand new ones that have not been loaded beyond their designed MSWP....
I can't guarantee you that you won't have a problem.... but that is my opinion on the impact of a regulator failure using a 4,500 psi tank.... and what I would do personally should it ever occur to me.... NOTE: this is an entirely different situation than using an increased fill pressure on a regular basis, the same thing does NOT apply because of the increased risk of metal fatigue caused by cycling above the MSWP....
Bob
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Thanks Bob. I was hoping you might comment here, as I saw your Brod thread, as well as noting your expertise. I have no information on the existing screws, and is another reason that I inquired. I may go with the idea to replace them if I ever have an overpressure event. I am planning on using a shortened version (ordered as such) of the JSA air tube, and we already saw from their tests what they can handle.
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And I would ask that you document your build because I too am considering such a build in the future... like 8 to 10 months.
For example, actually WHERE on the internet parts were sourced because what one person finds an other may not!
The thing I had considered as a drawback is regulator leak (creep) which would eventually bring the tube to tank pressure which happens with my Ninja regulated HPA Tank on one of my QBs (yah, not supposed to happen but IT DOES which is why I can't leave that rifle pressured)
But with the safety factors in the Marauder platform that should not be a negative determinant.
First question I am curious about: How long are you going to make the custom air tube so that you have sufficient shot volume?
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I will leave at least 100cc of air in the tube. I will decide the final length also based on chassis measurements once that arrives. The current setup runs over 80FPE with pellets, and I will be testing some heavier slugs, so likely want to stay around 100, following the 1cc per FPE rule. I will report back what I finally settle on.
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Interested in this build as well, got parts for a build myself and just need time and motivation.
Mike
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Tank:
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F232626950677 (https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F232626950677)
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Chassis
http://www.rarmsinnovations.com/product/rai-r016-modular-chassis-premier-version/ (http://www.rarmsinnovations.com/product/rai-r016-modular-chassis-premier-version/)
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Regulator and bottle block
WAR Cobra Externally Adjustable Regulator Bottle Block (fits Marauder and WAR rifles)
http://wickedairrifles.com/store.html (http://wickedairrifles.com/store.html)
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JSA SS valve
http://www.jsairrifles.com/Marauder-SS-Balanced-Valve-025_p_32.html (http://www.jsairrifles.com/Marauder-SS-Balanced-Valve-025_p_32.html)
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Here is a link for a cheaper 4500 psi bottle, I just ordered one two days ago so do not have in my hands yet but its over 50 bucks less for the same bottle at 92 shipped..
https://www.aliexpress.com/store/product/PCP-Paintball-Cylinder-High-Pressure-Tank-0-5L-Air-Tank-4500psi-300BAR-M18-1-5/2653128_32788828732.html?spm=2114.12010608.0.0.2c96136eu6X8zt (https://www.aliexpress.com/store/product/PCP-Paintball-Cylinder-High-Pressure-Tank-0-5L-Air-Tank-4500psi-300BAR-M18-1-5/2653128_32788828732.html?spm=2114.12010608.0.0.2c96136eu6X8zt)
Mike
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This is the one I got, in black.... https://www.aliexpress.com/item/500cc-Carbon-Fiber-HPA-Tank-Black-4500psi-Working-Pressure/32817495698.html?spm=a2g0s.9042311.0.0.vM1q66 (https://www.aliexpress.com/item/500cc-Carbon-Fiber-HPA-Tank-Black-4500psi-Working-Pressure/32817495698.html?spm=a2g0s.9042311.0.0.vM1q66)
Bob
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Yep, I use Aliexpress a lot as well, especially for electronic components. After shipping, the eBay one is only a little more, so I posted that one (figuring some might be wary of Aliexpress). Same bottle.
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Still have not decided about a barrel band, vs tensioning a barrel, vs floating it (with potential harmonic weights). For sure I will start with it just floating, and see how it shoots. Then I will decide.
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What are you planning to use for a barrel?.... Are you going to use a shroud, or sleeve it with CF to increase rigidity?....
Bob
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Tank:
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F232626950677 (https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F232626950677)
I could not find where its states which threads this bottle has so is it M18x1.5 or 5/8 x 18 threads. You need to know so you can match it to the right regulator threads or you may end up with two different threads that will not work together.
Just throwing that out there as a FYI.
Mike
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Looks identical to mine, which is 18 mm x 1.5 mm threads.... I have never seen a 4500 psi CF bottle that has anything else.... Since he is getting a Cobra Regulated Tank Block, he can just order the appropriate tank adapter anyways.... they have both available at WAR....
Bob
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I had not looked that close at all the different sellers of the 4500 CF tanks but it appears they only come in m18x1.5 as you stated. I guess only the aluminum bottles can be either or threads for our usage.
Good to know.
Mike
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Tank:
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F232626950677 (https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F232626950677)
I could not find where its states which threads this bottle has so is it M18x1.5 or 5/8 x 18 threads. You need to know so you can match it to the right regulator threads or you may end up with two different threads that will not work together.
Just throwing that out there as a FYI.
Mike
The model number is at least the same as what I ordered in M18x1.5 to match the regulator block.
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What are you planning to use for a barrel?.... Are you going to use a shroud, or sleeve it with CF to increase rigidity?....
Bob
I will use my .25 factory barrel and a slightly shortened Hill shroud at first. As I said, I still need to do the slug test that I was planning. It ended up being too windy last weekend to do it. I may keep it at 25, or switch to .30. If I switch it, then I guess the sky is the limit. I was actually brainstorming how to tension it with an inner sleeve, and still keep an outter shroud. There is certainly a large enough space between the existing barrel and the shroud for another cylinder.
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This is the one I got, in black.... https://www.aliexpress.com/item/500cc-Carbon-Fiber-HPA-Tank-Black-4500psi-Working-Pressure/32817495698.html?spm=a2g0s.9042311.0.0.vM1q66 (https://www.aliexpress.com/item/500cc-Carbon-Fiber-HPA-Tank-Black-4500psi-Working-Pressure/32817495698.html?spm=a2g0s.9042311.0.0.vM1q66)
Bob
HaHa, same one I just got for my WARP w/ 17" FLEX barrel!
Still have not decided about a barrel band, vs tensioning a barrel, vs floating it (with potential harmonic weights). For sure I will start with it just floating, and see how it shoots. Then I will decide.
My rifles get knocked around in real world hunting and I had problems with changing POI with the stock band so I went with the Hill which has a snug fit inside an o-ring. And it has a Picatinny rail at the bottom for flashlight or laser. Not sure a band would help that much being brought back towards the breach to clear the bottle would help but I probably would anyway
at first, on my Synrod .25 I used a whole slew of o-rings mounted on the barrel inside the shroud (like 20 at random spacing) to dampen and it does 'sort of work' as a 25 group, 5 shot each, before and 25 after group test had slightly smaller aggregate numbers, but small enough that it could just be statistical random noise too, HaHa.
I am a fan of tensioned barrels and did my first one on a BAM B-51 back in 6/04, shrouding with integral LDC too. It really sold me because the change in accuracy was phenomenal.
A collar at the breach and threaded air stripper on the muzzle with an aluminum tension column is how I would go. Everyone uses CF nowdays but I see aluminum as almost as light and SO much cheaper. I thickly grease up the steel barrel and slide the aluminum jacket on and tension then install in the gun. The regular shroud fits over the tensioned barrel and still has a small airspace for the air stripper to dump to.
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Carl, what you described for the tensioning is pretty much what I envisioned. Good to hear that it will work out well. I also currently use a Hill band on the .25, but as you know, it can't really be used after the bottle modification. I thought about a custom machined band that could clamp around the bottle and the barrel shroud as well. It would need to have close tolerances. Obviously, it can't dig into the bottle whosoever.
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I would look at a way to use the outer shroud to tension the barrel and still absorb the air to collect that noisy lead dust.... An arrangement like this possibly?....
(http://i378.photobucket.com/albums/oo221/rsterne/22%20cal%20Disco%20Double/Barrrel%20Tensioner%20Parts_zpsvunfq67a.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20cal%20Disco%20Double/Barrrel%20Tensioner%20Parts_zpsvunfq67a.jpg.html)
(http://i378.photobucket.com/albums/oo221/rsterne/22%20cal%20Disco%20Double/Vented%20Barrel%20Tensioner_zpspswrvq1w.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20cal%20Disco%20Double/Vented%20Barrel%20Tensioner_zpspswrvq1w.jpg.html)
(http://i378.photobucket.com/albums/oo221/rsterne/22%20cal%20Disco%20Double/Vented%20Tensioner%20Assembly_zpsc3ntz7kx.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20cal%20Disco%20Double/Vented%20Tensioner%20Assembly_zpsc3ntz7kx.jpg.html)
(http://i378.photobucket.com/albums/oo221/rsterne/22%20cal%20Disco%20Double/VBT%20in%20Shroud_zpsntf5owbh.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20cal%20Disco%20Double/VBT%20in%20Shroud_zpsntf5owbh.jpg.html)
I call that my "Vented Barrel Tensioner" or VBT.... I think it's pretty obvious how it works, no?.... You can't have baffle in front of it.... but it allows the shroud to work to absorb some of the residual muzzle pressure at least.... and only extends the barrel about 3" or so.... The tension is easily adjustable to change the barrel harmonics, and the Belleville washers provide much better temperature stability, always a concern with barrel tensioning systems....
Bob
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Very cool Bob. I love to see custom machined parts. I had not even thought of the temperature fluctuation impacts to tensioning. I will definitely come back and update the thread here as I progress.
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Unless you use identical materials for the barrel and shroud, temperature change makes a HUGE difference in tension.... If the barrel expands more than the shroud, it can cause complete loss of tension without the Bellevilles.... The longer the Belleville stack, the less percentage change in tension with temperature.... If the shroud expands more than the barrel, the tension increases, of course.... but again the Bellevilles minimize that (providing they don't go flat and bottom out)....
Bob
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Unless you use identical materials for the barrel and shroud, temperature change makes a HUGE difference in tension.... If the barrel expands more than the shroud, it can cause complete loss of tension without the Bellevilles.... The longer the Belleville stack, the less percentage change in tension with temperature.... If the shroud expands more than the barrel, the tension increases, of course.... but again the Bellevilles minimize that (providing they don't go flat and bottom out)....
Bob
So how many Bellevilles do you usually go for with a steel barrel and aluminum shroud?
I used two in my first one (the B-51 and have used three in other rifles but you are showing a lot more in your picture, and that is with a carbon fiber shroud which has a low coefficient of expansion, so basically just the steel to compensate for.
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Given the concerns over temperature changes, I wonder if one can obtain just as good accuracy without the tensioning concerns by using barrel weights at appropriate harmonic node points. Or is the tensioning approach so much better, that even with temperature fluctuations, it is better than such methods? Can you Bob, or someone more knowledgeable on this comment?
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I would think a barrel tensioning system would be easier- just crank on it little by little in either direction to increase or decrease tension- the barrel weight I think would be a touch more work, as you would have to slide it incrementally over the barrel whilst shooting groups... Unless there's a way to calculate how a barrel flexes during the shot cycle... JMHO. Either way you're tweaking and shooting groups until you find your settings- so I guess it's a toss up, really.
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Harmonic tuners can work great, but are 100% trial and error (as is finding the optimum tension).... There are two basic types, the slide-over "limb-saver" type rubber bushing, which you tune by sliding along while watching group size.... or the muzzle mounted, adjustable position weight, like rimfire shooter use.... It consists of a threaded weight (usually with locking collar or screw) that you move a tiny amount to fine tune the group size.... I understand that just a few thou can make a huge difference.... I plan on trying them on my current 6mm and .257 builds, which will be using 14mm barrels with huge 20mm OD CF sleeves bonded to them.... so they will already be incredibly still.... The harmonic tuner will, hopefully, be the icing on the cake....
(http://i378.photobucket.com/albums/oo221/rsterne/Parts%20for%20Sale/Barrel%20Tuner_zpsizerxqag.jpg) (http://s378.photobucket.com/user/rsterne/media/Parts%20for%20Sale/Barrel%20Tuner_zpsizerxqag.jpg.html)
Using 28 TPI has a reason.... each 30 deg. of rotation (1 hr. on a clock face) is 0.003", with 10 deg. being 0.001".... I don't know how you could use a limb-saver on a barrel inside a shroud.... but a muzzle (shroud) mounted tuning weight might work, I don't know.... One thing to be aware of.... changing the velocity or bullet can require retuning, regardless of which type of tuner you use (even tensioning)....
Bob
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The tank is arriving next week from China.
I ordered the WAR regulator at the same time, and the shipping date keeps getting pushed back. I am not sure about the reasons for delay. There was available stock the day I ordered. :-\
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Jim was able to finally ship my regulator today from WAR. Great.
Now I still need to return one piece of the chassis that arrived damaged for replacement.
Small steps...
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I have the regulator and carbon fiber bottle in hand.
The chassis did arrive, but is being swapped, due to it arriving with a scratch. The reseller has been great about the process so far. The RAI chassis is sharp at the corners up by the front, and one of them had penetrated the shipping box.
I did get a chance to measure where the chassis ends on the air tube. If I have JSAR make me a custom length tube that ends right where the chassis ends, so that the regulator block is the very next thing, without a gap, then the calculated plenum volume, with SS valve, and counting the smaller cylinder shape cut into the regulator theaded base, is 119CC.
119CC should allow me to reach my final goals with the gun.
I would like to reach 120 FPE if staying at .25 caliber, and a bit more if I jump to a larger and longer barrel. As I don't mind to run the regulator up around 3000psi, with 4500 in the carbon tank, I think this is realistic. The real aim here is a .22 rimfire replacement power wise.
In the gun which serves as the basis for this (.25 SS valve, .1875 porting, mds hammer, etc) I am up to around 85-90 FPE maximum. I think I will need to move beyond the .1875 ports, and do some probe (and possibly breech) work, to get the last bit of power out.
Comments welcome. I have not done any more calculations (yes, I should), only stating what the gun currently does, and where I want to go.
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I managed 117 FPE today (952 fps with 58.3 gr. BBT-FN) with my .25 cal BRod, running on 3000 psi with the 23.8" LW barrel.... The SS valve has a 1/4" port on a 15 deg. angle, the bolt probe is 3/32", which makes the area of the chamber the same as a 0.234" hole, so that is what I used for the transfer port.... This was for a dump shot, backed off a bit it shot 930 with the FN and 950 fps with the 55 gr. HP (ie 110-112 FPE).... I think this is the maximum at that barrel length without using a retracting bolt to increase the chamber area to full bore-size and using a matching 1/4" transfer port (6.8% more area for flow).... That alone would be good for a few FPE.... and of course a .257 cal barrel is 5.6% more bore area as well.... Without going to more pressure, a 28" barrel (17.6% longer) is the next logical step to find more FPE.... Multiply all those gains together and you have a third more FPE, which sounds like a lot, but my .257 Hayabusa, which met all those specs. maxed out at 160 FPE at 3000 psi, and gets a nice string unregulated at over 130 FPE.... Tethered or regulated at 3000 psi, a nice solid 140 FPE is possible without being too hard on air....
Bob
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I managed 117 FPE today (952 fps with 58.3 gr. BBT-FN) with my .25 cal BRod, running on 3000 psi with the 23.8" LW barrel.... The SS valve has a 1/4" port on a 15 deg. angle, the bolt probe is 3/32", which makes the area of the chamber the same as a 0.234" hole, so that is what I used for the transfer port.... This was for a dump shot, backed off a bit it shot 930 with the FN and 950 fps with the 55 gr. HP (ie 110-112 FPE).... I think this is the maximum at that barrel length without using a retracting bolt to increase the chamber area to full bore-size and using a matching 1/4" transfer port (6.8% more area for flow).... That alone would be good for a few FPE.... and of course a .257 cal barrel is 5.6% more bore area as well.... Without going to more pressure, a 28" barrel (17.6% longer) is the next logical step to find more FPE.... Multiply all those gains together and you have a third more FPE, which sounds like a lot, but my .257 Hayabusa, which met all those specs. maxed out at 160 FPE at 3000 psi, and gets a nice string unregulated at over 130 FPE.... Tethered or regulated at 3000 psi, a nice solid 140 FPE is possible without being too hard on air....
Bob
Thanks Bob, I saw your other thread and am now pondering plenum. I might should go more than the 119cc I would get with the nicest aesthetics of the block against the chassis, but chasing after power, I get the feeling I need to get it up around 150, so there would be a 5 to 6 centimeter gap between the chassis and start of the regulator block.
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You will gain a small amount by having more than 1 cc per FPE.... but I never bother.... The more efficient the gun, the less you gain from a larger plenum.... The plenum in my BRod is 85 cc.... in my Hayabusa it is the entire 460 cc reservoir....
You mentioned early in the thread using a stock MRod .25 cal barrel, which I believe are only 20" long.... That will really limit your FPE if you do that....
Bob
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I agree the 20 inch barrel regardless of porting will be very hard to push past 100 FPE without really ramping up the pressure to dangerous levels. To get you where you want you will need full bore porting (.250)and 24-28 barrel and some heavy lead.
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If you are producing 120 FPE at 1.00 FPE/CI, you use 120 standard CI of air to make the shot.... at 3000 psi, that is only 9.5 cc.... With a 120 cc plenum it would drop to 2762 psi during the shot, and the average would be 2881 psi.... With a 150 cc plenum the pressure would drop from 3000 psi to 2810 psi during the shot, with the average being 2905 psi.... With the entire 460 cc available in my Hayabusa, it only drops to 2938 psi, for an average of 2969 psi.... It is the difference in the average pressure that you use to calculate the potential FPE.... The 120 cc plenum loses 3% compared to the unregulated Hayabusa.... Going to a 150 cc plenum from 120 cc would only buy you back about 0.8%, which is only 1 FPE on a 120 FPE gun....
Bob
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If you are producing 120 FPE at 1.00 FPE/CI, you use 120 standard CI of air to make the shot.... at 3000 psi, that is only 9.5 cc.... With a 120 cc plenum it would drop to 2762 psi during the shot, and the average would be 2881 psi.... With a 150 cc plenum the pressure would drop from 3000 psi to 2810 psi during the shot, with the average being 2905 psi.... With the entire 460 cc available in my Hayabusa, it only drops to 2938 psi, for an average of 2969 psi.... It is the difference in the average pressure that you use to calculate the potential FPE.... The 120 cc plenum loses 3% compared to the unregulated Hayabusa.... Going to a 150 cc plenum from 120 cc would only buy you back about 0.8%, which is only 1 FPE on a 120 FPE gun....
Bob
Well thanks for that, and running the math. :)
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I received the new regulator and set it up with my .25 Marauder for basic testing. It held 3000 PSI for a few days, but today a few hours after filling the bottle up to 4000 PSI, it sprung a fast leak from the adjustment screw hole. So it will have to go back to WAR, or if Jim gives the go ahead (as to not void any warranty), I will ppen it up.
My scratched RAI chassis is back at the vendor, so the replacement ine for that should come in another week.
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I have the same bottle that bob linked. It has a nice gel coat that looks very nice indeed. I've been shooting it for two years now. I fill to 3600 for the .257 Talondor.
I tried a .25 barrel, well several factory walther bbls. Both choked, and with the choke removed. I ended up going with a TJ .257 BBL, and am very glad I did. Ultra accurate, and the selection of bullets is very good.
I cast bullets for it that are anywhere from 56 gr all the way to 110 grain. However, I recently shortened the 110 spire point down to 84 grains, and it is a real laser! ;)
It probably wouldn't hurt to put a carbon fiber sleeve on it for rigidity, as it is 24" long, and is shooting in the 180 fpe range with Dyotats valve, and139 fpe with R&L's valve. 8)
The .257 has proven itself to be one of the best short to long range cal's out there by quite a few shooters. Not once have I seen bad accuracy from a .257 matched to a TJ barrel.
Knife
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Bob at WAR sent me the diagram for the regulator, and is sending out a set of rebuild orings for the regulator after I indicated that I am fine with doing my own rebuild. Great support from WAR!
Today I should receive some Teflon rods that I ordered for making full bore port sized transfer ports. Thanks for the materials tip Bob. https://www.amazon.com/dp/B01BWK6D0M/ (https://www.amazon.com/dp/B01BWK6D0M/)
Still waiting on New England Airguns to ship out the replacement RAI chassis.
I will go ahead and full bore (oblong) port the existing .25 barrel to get around 100FPE. I will likely stop there for now, as I have a huge cache of .25 ammo. I will then likely convert to .257 at a later date, as a modification to the existing Brod project. Thanks all for the input about the barrels.
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After a lot of back and forth, I have just placed my order with JSAR for a custom length air tube. I selected 15.5 inches exactly. This gives a plenum volume of 130 cc's, which includes the volume in the SS valve I will be using. This is more than enough plenum for my .25 factory barrel, and will also give me room to grow when I inevitably want to play with a .257 or .30 barrel configuration. While a bit more plenum might be nice for later, it also puts the bottle and regulator further and further out in front of the gun, and I do not want it to be too front heavy. This should be a good compromise.
This arrangement leaves around a 11/16 inch gap between the end of the RAI stock and the start of the WAR regulator block. I wanted this gap to allow me to machine a barrel/shroud band a half inch or so thick to go there, as I do not like long floating barrels. The extra clearance will allow me to move it forward or backward a few millimeters in case it happens to sit on a bad spot for harmonics. In real life usage, the barrel may get slightly pushed on one way or another while hunting, and I don't want the POI to change so easily. This should solve that, without needing a bulkier barrel band further down around the carbon fiber tank, which I wouldn't want anyway, as I will put a neoprene cover on the bottle.
This sizing also allows my 500cc bottle end to stop just a millimeter or two before the end of my custom anodized shroud, which is 22 inches long, plus having a 1/2-20 adapter on the end for a LDC. So the bottle will never end up past the end of the barrel with shroud. This custom shroud is a replacement one that I obtained after the mishap I had with my factory one that some of you may remember (bubbled it out a bit at the threading).
Just by chance I saw a Youtube video of a .30 Marauder that Travis made, and it was using the same or a very similar chassis as I am using, and a similar tank block (looks like without a regulator though). This gave me a nice idea how the gun is going to look when I am done, as it will be close to the same, except with the small gap between the chassis and the tank block.
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Have taken some measurements and will proceed to bore out the valve exhaust to a full .25 inches after a .375 exhaust refacing to match the Teflon rod TP.
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Valve with new internals from JSAR, but still with default port and jet (posted as someone asked me about them).
I will be back after the modifications, as I was delayed by needing to order a particular end mill.
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Followup for 2 vendors:
I finally rebuilt the WAR bottle block with regulator. It's all good now and holding air. It failed due to two orings in swapped positions; a very easy assembly mistake to make. No harm, no foul. Jim offered a free rebuild, but I did it myself and he gave me extra oring sets along with the schematic.
I also received the replacement stock a while back for the scratched one from New England Airguns. They paid for the shipping both ways to right the situation, so kudos to them as well.
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I finally had time to mark up a picture of modifications for my receiver to allow deeper pellet seating, important for after port elongation for the full .25 sized transfer port from JSAR, as well as full retraction of the probe from the port for firing. I am hopefully outsourcing this machine work to JSAR.
My upper/receiver is actually marked Armada on the side. I ordered this from Hill, and assume it is just a Crossman Armada one. I did this because I want the rifle to match the RAI stock fully with Picatinny rails. Additionally, the scope mount that I want to use is also Picatinny. I discovered that the back of the bolt with this receiver doesn't actually touch the back of the receiver. As you can see in the picture, there is a small gap. If we mill out the internals a bit, we can use that extra space to ensure pellets are seated past the elongated port. ;D
With additional milling, we can make a retracted position as well, using a very short sleave occupying about half of the probe tip, to reseal the breach oring.
Critique and feedback welcome. I have sent these requirements and some others to JSAR for job quotation.
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The extra bit of travel for the bolt to push the pellets past a larger barrel port works. A 5min job with dremel. Limiting the barrel port to .19 to prevent the pellets falling in the transfer port, nonsense.
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The extra bit of travel for the bolt to push the pellets past a larger barrel port works. A 5min job with dremel. Limiting the barrel port to .19 to prevent the pellets falling in the transfer port, nonsense.
I don't mean literally falling through. I mean rather not drilling out the port to a full .25, as some have reported that some pellets may begin to dip down a bit when traveling across the port, and causing marking in the side of the pellet. I thought that this has been confirmed by then oushong out the pellet with a rodnfor inspection. If this is false, then I am all ears.
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David,
Check this out compliments of TNT76:
https://www.gatewaytoairguns.org/GTA/index.php?topic=111215.msg1064198#msg1064198 (https://www.gatewaytoairguns.org/GTA/index.php?topic=111215.msg1064198#msg1064198)
You should see if JSA can make something like that. A drop in retractable bolt for the Mrod platform.
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Lloyd has done a retractable bolt in an MRod receiver, suggest you PM him or search it.... I believe he rotated the bolt further and milled the slot out through the side of the receiver in the retracted position.... You only need to do one side, whichever way you want YOUR gun to operate.... and there should be metal between the two slots to prevent the bolt from rotating back up before you fire, IMO....
Bob
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Bob, are you talking about the common J slot ?
I think Lloyd made a retractable lever design (one time off) years back
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Two things here. I need it to changeable for left and right shooters, and I don't want a side slot. That is why I came up with the idea in the picture.
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Got it!.... Yes, Tim, I was talking about the "J" Slot first posted by Sean Pero, I believe.... The advantage of milling the slot out through the side is that you can remove the stud that locks the bolt and cocks the hammer from the side of the receiver, without removing it.... and slide the bolt out the back to change calibers, or for cleaning the barrel.... but it doesn't look as nice.... and not reversible.... Make sure the bolt can't easily rotate to the unlocked position, you don't want it flying back on firing....
I hadn't seen that retractable probe by tnt76 before, very clever.... You can make the probe large enough to spread the load over the back of a slug so that it doesn't dent it.... while cleaning up the airflow.... NICE !!!
Bob
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I received the machine work quote from JSAR today at a very fair price, so will be sending off some of the parts this week for additional work. This will also include threading the end of my barrel for an aluminum Hill "air stripper," and a few other things.
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Here is an example of one of the custom swagged slugs that I had made for this build. On the ledt is a regular JSB Exact King Heavy 33.95 grain pellet. On the right is the custom slug for tray loading due to length, hollow point, boat tail, and 65 grain. I can't wait to try these once the gun is built up.
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I received the custom length air tube from JSAR today. It looks really great, although it is 15.5625 inches, instead of the specified 15.5. It will not hurt anything or matter much though.
I have been too busy with work to send them my other parts for machining, but hope to get to it in the next week.
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Sounds like and awesome build. I cant wait to see it all together. 8)
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I just noticed that my air tube has a hole for a factory valve meter screw. Arghh. Why, why, why. Why would I need that hole there when I also specifically had the transfer port hole specified for a JSAR valve. :(
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I just noticed that my air tube has a hole for a factory valve meter screw. Arghh. Why, why, why. Why would I need that hole there when I also specifically had the transfer port hole specified for a JSAR valve. :(
Due to numerous complaints all tubes have them now its tied into the C&C program.
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Small update. I finally sent some parts to JSAR for machining. I will be using their large SS valve, rather than mess with any teflon transfer ports. This should also make barrel changes easier, as I am also pricing out a very long .30 barrel since some states are starting to allow .30 and up for hunting, where they didn't before. This means more research and finding a good slug to barrel match. I will read around and am especially looking for information on some of Bob's slug performance at common .30 available twist rates. I will look into Nielsen and Ratsniper .30 slugs as well.
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I just noticed that my air tube has a hole for a factory valve meter screw. Arghh. Why, why, why. Why would I need that hole there when I also specifically had the transfer port hole specified for a JSAR valve. :(
Due to numerous complaints all tubes have them now its tied into the C&C program.
Ah, ok. Understood. I will just hit that spot of the valve with a drop of black paint or something.
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Update:
Travis indicated that the reason my WAR bottle regulator didn't screw all the way down is the need for a few more thread turns down in my tube. So I sent him my tube, and this burns yet another week in wait time.
In the meantime, I am thinking about an additional barrel. Originally, I was very interested in a 257. However, with the off chance that I might ever try it with game and the new Texas rules, I am thinking about a .308. This might also make it easier to fit heavier slugs in the breech without having to make a long cone slot along the edge to get the slug in the gap (or at least a smaller one if it is still needed). This will also maximize what the build is capable of in several areas (plenum, biggest possible barrel with breech block, etc).
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Update:
Parts will be ready this week for the .25 factory barrel build. I am starting to get excited for this one.
After an enlightening discussion with Travis, I have moved the .308 idea to the next project, as I want to also tension that barrel. So a whole other upper/breech bored out for a larger barrel diameter (for stiffness) and pinned from the sides for the tensioning will be in the requirements.
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Update:
The machine work is done. Now waiting on the JSAR shipment so I can assemble the Brod. I am hoping to assemble everything and start tuning next week.
:D
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Bob, are you talking about the common J slot ?
I think Lloyd made a retractable lever design (one time off) years back
If you are talking about the one he has a YouTube video for, where the bolt recedes when the lever is pushed all the way down...I wish someone would offer those, and with a pic rail on top.
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I received the parts from JSAR.
The retracting bolt breech mod could only be done on one side, not both due to the hammer cocking bolt head that needs to be pushed back by the similar one on the bolt, and needing to retain a side for them to slide along. So the retracting bolt is right handed.
The full bore porting is set up to us .25id tube, NOT the JSAR large metal transfer port. This is due to the close proximity of the mag well. If the port is opened up enough for the JSAR metal transfer port, then it would break through or leave that side too weak, creating a safety hazard.
They did a great job of threading the barrel end for my metal air stripper, as well as adding more threads to the JSAR air tube end to fully seat my WAR bottle regulator.
Time to assemble it all!
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I did a quick build-up, and the valve has a leak. Time to tear it back apart and find out if there is a torn poppet oring, or it needs burnishing.
Edit: OK, the leak is fixed. I opened the valve, wiped everything down, did a quick poppet spin with a drill, Krytoxed everything, and reassembled it. I will have to do an overnight test to be sure it doesnt have a slow leak.
Hoping to do some initial tuning tonight.
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Initial results are not so good. I am shooting the 43gr Eunjins at only 850 fps. Before the retractable bolt modification, I was getting a little over 900fps. I changed the breech oring, but this did not help. More hammer is not imcreasing it, and I suspect that either the tube transfer port needs reseating, or the dwell is too short. I will check the transfer port first and then if this doesn't resolve it, pull the jet out of the valve just to test.
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TP was fine. I pulled the jet, and was off to the races... 43gr Eunjin hit 955 FPS. Tired, so stopped right there for tonight. The valve behaves quite different now with the newer internals, compared to before. I will start tuning tomorrow. :D
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;D
I remembered my custom heavy slugs, so did one final test for tonight.
65gr boattail, turned the hammer in, and got 833 FPS!!! That's exactly 100 FPE, which was the goal. No idea about accuracy yet obviously, bit I'm happy to see that goal met.
Tuning and shot strings tomorrow!
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Nice job on hitting 100 fpe David! Congrats, your hard work and patience has paid off.
Post up a picture of the Brod when you get a chance.
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Thanks Randy!
I set the scope and rangefinder on top for a quick picture. There is still a lot to do in terms of tuning, and setting it up.
I will likely add a neoprene band to the carbon fiber tank to cover the white label, or wrap the front components with camo wrap.
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She is purdy!! I can't wait to read more!!
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What output pressure are you running on the tank block to get your 100 FPE with the 65 gr. bullet?....
Bob
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What output pressure are you running on the tank block to get your 100 FPE with the 65 gr. bullet?....
Bob
3300 psi.
Barrel port is .2 round (not oblong)
JSAR valve and TP are .25
Valve screws are stainless, not factory. Travis called them upgraded, but I won't push my luck too far.
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Nice build . I’m wondering why crosman has yet to build a bottle gun . I know I would have a real good look if they offered one .
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Stainless screws are not necessarily stronger than the stock screws, it depends on the grade of SS....
https://www.gatewaytoairguns.org/GTA/index.php?topic=127914.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=127914.0)
Bob
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Stainless screws are not necessarily stronger than the stock screws, it depends on the grade of SS....
https://www.gatewaytoairguns.org/GTA/index.php?topic=127914.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=127914.0)
Bob
Thanks Bob. I am well aware, and why I alluded to not having the engineering data.
I meant to ask Travis to qualify what exact kind they were but forgot it amongst the other things we discussed.
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I realized this morning that my tanks are all low, and my compressor is not set up. I took one bottle for fill, but their cascades were also low. It will be at least Monday before I can get a full fill and run tuning strings.
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Sorry if I missed it but what spring setup and hammer are you running at the moment
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David
Nice looking Brod! It would awesome camo wrap on the LDC & bottle.
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Sorry if I missed it but what spring setup and hammer are you running at the moment
I am using the JSAR MDS only hsmmer (not the brass core one), and a shorter than factory yet stiffer spring with a Speed Dial. This was perfect with the earlier JSAR valve thst I had, but I noticed the valves now with the revised internals, it can handle more hammer, so I will likely be experimenting some starting tomorrow when I get my air fill going.
Here is the Speed Dial, which is handy for easily putting a spring back to an exact know position without having to count turns. The Marauder rifle variant provides for 6 turns. I may modify this to do more. http://www.airgunsofarizona.com/parts/custom-speed-dial-100/ (http://www.airgunsofarizona.com/parts/custom-speed-dial-100/)
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David
Nice looking Brod! It would awesome camo wrap on the LDC & bottle.
Thanks Randy!
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Sorry if I missed it but what spring setup and hammer are you running at the moment
I am using the JSAR MDS only hsmmer (not the brass core one), and a shorter than factory yet stiffer spring with a Speed Dial. This was perfect with the earlier JSAR valve thst I had, but I noticed the valves now with the revised internals, it can handle more hammer, so I will likely be experimenting some starting tomorrow when I get my air fill going.
Here is the Speed Dial, which is handy for easily putting a spring back to an exact know position without having to count turns. The Marauder rifle variant provides for 6 turns. I may modify this to do more. http://www.airgunsofarizona.com/parts/custom-speed-dial-100/ (http://www.airgunsofarizona.com/parts/custom-speed-dial-100/)
First time ever hearing of the speed dial. Is there a way to lock it down once your desired tune is found? How have you liked it and how much does it protrude out the end cap or does it replace it all together?
Peter
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I can't recall now if it replaced the end cap or screwed into it, but I think it had just screwed into the factory one after removing the insert. I will take a picture the next time I have it out of the stock. It does have a small locking level on the edge of the dial area. If I was going for pure efficiency, I would certainly prefer a SSG setup, but for this purpose, where I have a large bottle, and want to precisely dial the spring in or out for pellet versus heavy slugs, it's great.
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I noticed this morning that there is still a very slow leak somewhere. I had done a 48 hour test previously with tube and regulator, so the leak must still be coming from the valve. On the next teardown, I will replace the poppet orings, as well as air tube static orings for both valve and regulator (as some trash from the thread additions could have nicked somewhere before I cleaned it out).
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I can't recall now if it replaced the end cap or screwed into it, but I think it had just screwed into the factory one after removing the insert. I will take a picture the next time I have it out of the stock. It does have a small locking level on the edge of the dial area. If I was going for pure efficiency, I would certainly prefer a SSG setup, but for this purpose, where I have a large bottle, and want to precisely dial the spring in or out for pellet versus heavy slugs, it's great.
Ok. Gotcha. Thanks.
Peter
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I have switched to the JSAR hammer with brass insert. Checking my notes from the earlier prototype setup (used old JSAR valve internals before the revision), I confirmed that I was having to use way more spring now to produce the similar ranges, so I upped the hammer weight in order to keep the spring requirement down. Air is now flowing, so hopefully I can run some strings this week.
New maximum with the heavier hammer and full spring tension on my speed dial with a heavier short spring is:
102.5 FPE @3300 psi with 65gr slug (843FPS)
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That thing is shooting HOT! Nice build my friend. My personal record is 111fpe shooting 73 grain spritzers at 3400psi with a stock barrel using a bored to the max stock valve and a 22lb spring and 90 gram hammer LOL...Glad those days are over.
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That thing is shooting HOT! Nice build my friend. My personal record is 111fpe shooting 73 grain spritzers at 3400psi with a stock barrel using a bored to the max stock valve and a 22lb spring and 90 gram hammer LOL...Glad those days are over.
Hahaha. You can keep that record, that 22lb spring, and sore cocking finger. Impressive. I would be afraid of the sear failing with that much spring!
I have seen many duplicates on the chrono already. I can't wait to have time this week to run strings and check the ES. That WAR regulator is really solid, and the JSAR valve seems much more stable with the new internals and a heavier hammer/spring behind it than my earlier prototyping.
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I agree I dont know how the sear survived but it was only set up for a few days just for bragging rights. It was a bear to cock and double loading was a frequent event.
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OK, after serveral test shots to find my boundary conditions...I settled on the hammer striker turned in all the way flush. This gives me 5 full turns of the speed dial worth of hammer free flight and 1 additional turn with no free flight. At 5 turns in you can immediately hear the valve start to wheeze heavily and waste air.
I use Eunjins as a proxy for testing with the heavier custom slugs for now since they are cbeaper and I have many tins of them.
1st string I will share, maximum power without the wheezing and waste. This is with the speed dial at 450, in other words half a turn from 500, so there is half a turn of free flight. I will run it again at various lower settings to see about more efficiency, but this is a nice tune already for high power as it will allow 2 full magazines to be shot before coming off the regulator using the 500cc tank with 4500 psi. If I swap in the 65gr slugs, the FPE are over 100. I stopoed here because I noticed the bolt lug getting loose and grinding on the top of the air tube. So I will tear it down now and also try to solve that slow leak.
"High Power Hunting Tune"
Name: H0; Speed Dial 450; Eunjin 43gr; Regulator 3250psi; JSAR valve and TP at .25 porting; barrel at .2 porting; JSAR MDS hammer with brass insert.
Notes: 4350 -3720 psi on 500 cc tank
Shots: 8
Average: 979 FPS
SD: 3 FPS
Min: 976 FPS
Max: 984 FPS
Spread: 8 FPS
Power Factor Average: 42
Power Factor Low: 41
Power Factor High: 42
Barometric Pressure: 30
Temperature: 88
Weight: 43.0 grains
Avg FPE/cu in/shot = .55
Avg PSI/shot 79
Index Velocity Ft/lbs
1 984 92.4
2 981 91.9
3 982 92.1
4 981 91.9
5 977 91.1
6 976 90.9
7 977 91.1
8 978 91.3
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Nice hunting tune at +90fpe! Ya gotta love those numbers ;)
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Here is the picture of the Speed Dial.
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Nice hunting tune at +90fpe! Ya gotta love those numbers ;)
The really nice part is that I can back off the spring and lose only 10 to 15 FPS (3 to 4 FPE), and the air usage is about half. I can set it like that, and go out all day. ;D
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Ok, so I found the slow leak. It is coming from the large assembly lug that holds in the internals of the WAR bottle regulator. I had not suspected it at first because it held fine for several days in the earlier prototype rifle. Soapy water confirmed it. I will fix that tomorrow, and then get back to tuning around.
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Nice hunting tune at +90fpe! Ya gotta love those numbers ;)
The really nice part is that I can back off the spring and lose only 10 to 15 FPS (3 to 4 FPE), and the air usage is about half. I can set it like that, and go out all day. ;D
Sweet!!!
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I fixed the WAR bottle regulator valve leak earlier today. There was 1 tiny leak at one of the gauges, and 1 tiny leak at the large hex lug for the internals. It has sat now with a fill whip with a digital gauge attached (with the fill tank closed of course), and it hasn't moved off 4410 psi for several hours. So I think I finally licked the leak. :D
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I fixed the WAR bittle valve leak earlier today. There was 1 tiny leak at one of the gauges, and 1 tiny leak at the large hex lug for the internals. It has sat now with a fill whip with a digital gaige attached (with the fill tank closed of course), and it hasn't moved off 4410 psi for several hours. So I think I finally licked the leak. :D
I feel some serious smack about to be laid down on and uninformed critter...Sweet build you have my friend.
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They might actually get a break, as I am not sure we will go out to the lease again until fall, except for a cleanup. Hmm, maybe I should clean some varmints.
In the meantime....look at what I have. Heh. I also have some larger aluminum tube to match it. I might use this on the next build. I can only use it on this one if I marry the smaller tube to the larger one with a lathe made coupler, or add a riser to the breech.
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Here comes the results if the first time out to test ammo with the Brod.
Conditions of the next 6 posts.
Shooting fully prone
This position is a bit new for me especially with this stock and high Eagle Vision mount. I need to practice. Even with the RAI stock adjusted fully up, I still have to angle my cheek up a bit. I have to say I prefer my low scope rings, but I got the Eagle Vision mount for my infrared camera setup. A relative and I may set up a proper benchrest in the future.
Gusty moderate winds
Scope not adjusted or zeroed at all. Aimed for center target.
All rifle settings left the same. Filled between groups, so no shots off regulator. 3400 psi
8 shots per group
Circled shots are ones I know I pulled.
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43gr Eunjin, 32 Yards
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55gr Boattail Hollow Point custom Ratsniper; 32 yards; 97FPE
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At that power level I would get a harmonic tuner and start finding the sweet spot.
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59gr NSA Hollow Point; 32 yards
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65gr Boattail Hollow Point custom Ratsniper; 32 yards; 100FPE
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Now moved out to 50 yards. I only had time to shoot the 55 and 65 grain custom Ratsnipers. Eunjins didn't make the cut anyway.
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65gr Boattail Hollow Point custom Ratsniper; 32 yards; 100FPE
exceptional.
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55gr Boattail Hollow Point custom Ratsniper; 50 yards; 97FPE
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65gr Boattail Hollow Point custom Ratsniper; 50 yards; 100FPE
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65gr Boattail Hollow Point custom Ratsniper; 32 yards; 100FPE
exceptional.
Thanks. I liked those too, but things got a bit interesting at 50 yards. The 55 and 65grain slugs both opened up a bit more than I wanted. They are in similar regions as they shot at 35 yards, so they aren't spiralling or anything, but I would like to tighten them up. A tuner or tensioner might help.
I also want to make a barrel band for near the middle where the stocks ends, but before the tank block. I am good at bumping things, so want one that holds the barrel with the pressure of an oring set inside the barrel band loop. That way it is still semi floating, but can reduce some vibration while also protecting from bumps to the barrel.