Author Topic: Brod build: 100 FPE; stock barrel; shot pic updated (Read 12542 times))

PCPhack · « **on:** January 27, 2018, 04:14:00 PM »

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.

rsterne · « **Reply #1 on:** January 27, 2018, 07:03:28 PM »

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

PCPhack · « **Reply #2 on:** January 27, 2018, 09:13:43 PM »

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.

Kinetic45^ · « **Reply #3 on:** January 27, 2018, 09:48:49 PM »

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?

PCPhack · « **Reply #4 on:** January 27, 2018, 09:58:16 PM »

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.

Buldawg76 · « **Reply #5 on:** January 27, 2018, 10:29:31 PM »

Interested in this build as well, got parts for a build myself and just need time and motivation.

Mike

PCPhack · « **Reply #6 on:** January 27, 2018, 10:30:48 PM »

Tank:
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F232626950677

PCPhack · « **Reply #7 on:** January 27, 2018, 10:33:10 PM »

Chassis

http://www.rarmsinnovations.com/product/rai-r016-modular-chassis-premier-version/

PCPhack · « **Reply #8 on:** January 27, 2018, 10:35:24 PM »

Regulator and bottle block

WAR Cobra Externally Adjustable Regulator Bottle Block (fits Marauder and WAR rifles)

http://wickedairrifles.com/store.html

PCPhack · « **Reply #9 on:** January 27, 2018, 10:36:49 PM »

JSA SS valve

http://www.jsairrifles.com/Marauder-SS-Balanced-Valve-025_p_32.html

Buldawg76 · « **Reply #10 on:** January 27, 2018, 10:52:44 PM »

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

Mike

rsterne · « **Reply #11 on:** January 27, 2018, 11:07:52 PM »

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

Bob

PCPhack · « **Reply #12 on:** January 27, 2018, 11:31:58 PM »

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.

PCPhack · « **Reply #13 on:** January 27, 2018, 11:35:14 PM »

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.

rsterne · « **Reply #14 on:** January 27, 2018, 11:39:58 PM »

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

Buldawg76 · « **Reply #15 on:** January 27, 2018, 11:58:10 PM »

Quote from: PCPhack on January 27, 2018, 10:30:48 PM

Tank:
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

rsterne · « **Reply #16 on:** January 28, 2018, 12:01:16 AM »

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

Buldawg76 · « **Reply #17 on:** January 28, 2018, 12:12:57 AM »

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

PCPhack · « **Reply #18 on:** January 28, 2018, 12:45:43 AM »

Quote from: buldawg76 on January 27, 2018, 11:58:10 PM

Quote from: PCPhack on January 27, 2018, 10:30:48 PM
Tank:
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.

PCPhack · « **Reply #19 on:** January 28, 2018, 12:49:38 AM »

Quote from: rsterne on January 27, 2018, 11:39:58 PM

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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Brod build: 100 FPE; stock barrel; shot pic updated

Author Topic: Brod build: 100 FPE; stock barrel; shot pic updated (Read 12542 times))