GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Big Bore AirGun Gate => Topic started by: Fur-n-dirt on February 07, 2014, 10:46:40 PM
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I shot the Extreme for accuracy today...
Filled the gun to 4000psi using a modified Lee115 grain to HP. My chronograph shows the first shot averages 1035 fps.
I shot three group strings at 4000 psi. First three shot group was .7" ctc and second group was .5 ctc at 50 yards. Excited to shoot more and see where the numbers fall.
Not bad considering using 5x scope.
I did notice that the second shot was consistently lower by at least 4"! The third shot was 1.5 to 2" below that.
After talking to Brent, I'm finding out the gun is designed to shoot heavier bullets and at higher pressures.
I love these bullets, I want to figure out how to get two consecutive shots. Considering the bullet pressure exerted on the valve, seems a lighter spring can help. Any suggestions on getting better performance is greatly appreciated.
More to come.
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You need to Chrony all the shots to know how to tune the gun.... How can the groups be 0.7" and 0.5" CTC and yet the shots drop 4" and 1.5-2" ?
Bob
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You need to Chrony all the shots to know how to tune the gun.... How can the groups be 0.7" and 0.5" CTC and yet the shots drop 4" and 1.5-2" ?
Bob
Hi Bob,
Let me clarify. When I counted groups, it was based on the "first shot" filled at 4000 psi. So, the two groups reported was based on shots at 4000 psi.
I chronographed the other day.. At 3800 psi, the velocities for the first three shots were 1054 , 984, and 924.
Today, when I was shooting , the pressure dropped from 4000 psi to 2500 psi after three shots.
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Let me get this straight.... Three shots with 109 gr. bullet (that's what mine weighed, same mold as yours)....
1054 fps = 269 FPE
984 fps = 234 FPE
924 fps = 207 FPE
Total FPE = 710 FPE
Pressure used = 1500 psi (4000 - 2500) = 103 bar.... Do you know what the volume of the air reservoir is?....
IMO, the spring is wayyyyyyyy too stiff for that bullet weight at that fill pressure.... The quickly dropping velocity is part of the reason for your dropping POI....
Bob
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Bob,
Yes. Those numbers stated in your last reply is correct. That is my situation.
Reality is sinking in that this stock gun likes heavy bullets and at high pressures. Very high!
It appears that I am way under the bell curve.
Your suggestion about being stiff confirms my initial guess stated at the beginning of this thread.
I really like this bullet. I did some calculations and this bullet should fly great with this barrel twist. And it seems to be the case or else I wouldn't have gotten that .5 ctc group (and I've only just started).
It would be awesome to have a consistent 3 shot fill with this bullet.
So, the question is, where do I go from here? Should I plug and chug with lighter springs? A member had stated using a lighter spring in his extreme, but I thought it was a higher caliber ( need to check). I guess I could start with this one and adjust?
For tank volume, I don't know; however, OUTSIDE dimensions are approximately 24 inches by 1 3/8"
Thanks for your help guys!
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What hammer spring are you using. My Extreme .308 gets 5-7 consistent shots.
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I would assume the wall thickness is 0.125", which would result in an ID of 1.125" and a safety margin of 3.1:1 at 4500 psi, assuming CrMoly tubing.... That works out to 1 CI of volume per inch of reservoir length.... We need the inside length (front of valve to back of fill fitting), but if we assume it is the 24" you gave, then we can use 24 CI to do the efficiency calculation....
The total volume used for the 3 shots would be 24 x 103 = 2472 CI to develop just 710 FPE, so that works out to 710 / 2472 = 0.29 FPE/CI, which franky, is pitiful.... This is not uncommon with Big Bores, my DAQ .308 Exile ran 0.38 FPE/CI the way I got it, and simply by setting the hammer spring (compressing it fully and then letting it rebound, which shortened it nearly an inch) I got the efficiency up to 0.88 FPE/CI, which while not great, is at least acceptable.... The crazy thing is that I went from 3 shots of 836, 786, 742 from 3000 psi down to 1800 stock, to 6 shots of 826, 833, 832, 824, 811, 792 from 3200 psi down to 2050.... In other words, I lost only 3 fps at 3000 psi, and I got 6 shots instead of 3, and my 6th shot was faster than the 2nd shot stock.... I have no idea why Big Bore manufacturers insist on overspringing their guns, the only logical explanation is that their customers are willing to accept poor efficiency, maybe they get a kick out of hearing that loud BOOM !!! as all the air flies, wasted, out the end of the barrel....
IIRC, fitting a hammer spring preload adjuster is not easy on the Extreme, as the stock is in the way.... I'm not so sure that is the case, perhaps a small screw could be offset near the top of the rear plug, moving a sliding spring seat, but let's assume for now you can't, so you have to change springs.... The easiest thing to do is to get a couple more stock springs and first, try setting one, and if that doesn't shorten it, then cut off a coil or two at a time until you get what you want.... I recently played around with hammer spring preload on my Disco Double, which is unregulated, with the following results....
(http://i378.photobucket.com/albums/oo221/rsterne/30%20cal%20Disco%20Double/30DiscoDoubleHammerSettings_zps443bcea0.jpg) (http://s378.photobucket.com/user/rsterne/media/30%20cal%20Disco%20Double/30DiscoDoubleHammerSettings_zps443bcea0.jpg.html)
You will note that with the 50 gr. pellets, the last 4 turns of preload (0.168") did nothing but waste air, and with the 70 gr. bullets, the last 2.5 turns (0.105") didn't gain any velocity either.... However, even though the velocity didn't increase with the preload at maximum, the gun used wayyyyyyy more air.... I'm guessing your gun is currently set up at 4000 psi so that the velocity is way up on the plateau, and the efficiency way down.... One thing for sure, you need to reduce the hammer strike.... and/or run 4500 psi....
Bob
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Fur-n-dirt.....did you get a spare spring from Brent with the Extreme? They have the stock heavy spring which comes with the gun (Brent's favorite) which has the bell curve well above 4000psi and a lighter spring which should get you a bell curve around 4000. The even lighter spring (Century Spring #2894) which I told you about that I use in my Extreme 45 will drop the bell curve to the lower 3000's and give you more consistent shots as the pressure drops only about 3 or 400 psi per shot. All of this assumes that Brent is using the same springs in both the 308 and 45. You could check with him to find this out. Also as I noted before the velocity only drops about 10% in my gun from the heaviest spring and 4000 fills to the lightest spring and 3000 psi fills.
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Grumpy - How the *(&^ are you getting 5 consistent shots? I have the light spring. What psi/bullet?
Bob - That's a big eye opener. I reproduced your calcs on Sike's site. Definitely room for improvement! Thanks again for the numbers, this helps.
Shamu25- I only got one spring for my gun. :-( It's the light spring as I've been told. And I didn't even get the gun case or scope mounts.
I think the consensus should be to go to a lighter spring. I think I'll go both routes; get the after market spring and request a couple of stock springs from Brent. Try and work backwards into a consistent shot string. I just need to be careful ordering springs that don't set over time from material or storage spring position.
Shooting at 4500 psi is not practical. I have a shoebox that fills up to 4500 or so. :-(
Thanks!
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Easy solution.... set the spring by compressing it fully before installing it.... That way it will basically never get shorter unless you store it at coil bind....
Bob
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Its not as hard as you think. Check out my buddy Jim's videos on his Extreme .308
http://www.youtube.com/watch?v=uQsVfU5Jw0c# (http://www.youtube.com/watch?v=uQsVfU5Jw0c#)
http://www.youtube.com/watch?v=SnKByvAcDcM# (http://www.youtube.com/watch?v=SnKByvAcDcM#)
He also has a few others with his .308 I have not linked. My gun is vitually identicle to his except I got a slightly longer 30" barrel
Dave
Grumpy - How the *(&^ are you getting 5 consistent shots? I have the light spring. What psi/bullet?
Bob - That's a big eye opener. I reproduced your calcs on Sike's site. Definitely room for improvement! Thanks again for the numbers, this helps.
Shamu25- I only got one spring for my gun. :-( It's the light spring as I've been told. And I didn't even get the gun case or scope mounts.
I think the consensus should be to go to a lighter spring. I think I'll go both routes; get the after market spring and request a couple of stock springs from Brent. Try and work backwards into a consistent shot string. I just need to be careful ordering springs that don't set over time from material or storage spring position.
Shooting at 4500 psi is not practical. I have a shoebox that fills up to 4500 or so. :-(
Thanks!
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And I cannot pass up the chance to post a pic of my baby lol
(http://www.airgunsforum.com/picture.php?albumid=17&pictureid=841)
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And I cannot pass up the chance to post a pic of my baby lol
(http://www.airgunsforum.com/picture.php?albumid=17&pictureid=841)
Thanks David.. This confirms that you need to be around 4500 psi to be on the bell curve for ~120 grain. However, he switched to much lighter weight on the fourth shot! (I like Cricket, I bought his left over ammo for the extreme).
For me, its not practical to shoot at 4500 psi, with a 4500 to 4700 psi SCBA tank.
Hopefully, I can come up with something. The barrel twist should be perfect for this length of bullet.
David, do you have any groups or ammo recommendations that you would like to share? Greatly appreciated.
Oh, here's mine. Got a vortex scope on sale. These extremes are down right sexy. ;D ;D
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/IMG_07071_zps977c96c0.jpg) (http://s258.photobucket.com/user/bginvestor/media/Rogue/IMG_07071_zps977c96c0.jpg.html)
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/IMG_07101_zps351b111b.jpg) (http://s258.photobucket.com/user/bginvestor/media/Rogue/IMG_07101_zps351b111b.jpg.html)
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Have someone make you a power adjuster, bust out the dremel and take your time fitting it to the stock.
I had to do that with my Corcoran stock - I wanted to be able to tune it so it was a necessity.
I think it came out quite nice!
:)
I would ask the maker of the rifle to manufacture one for you. I think he should offer those as an option anyway.
(http://i94.photobucket.com/albums/l83/mhossack/My%2022xx%20Airgun%20Build/th_18.jpg)
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Have someone make you a power adjuster, bust out the dremel and take your time fitting it to the stock.
I had to do that with my Corcoran stock - I wanted to be able to tune it so it was a necessity.
I think it came out quite nice!
:)
I would ask the maker of the rifle to manufacture one for you. I think he should offer those as an option anyway.
(http://i94.photobucket.com/albums/l83/mhossack/My%2022xx%20Airgun%20Build/th_18.jpg)
Very nice!
An adjuster has been brought up to Allen from extreme on this forum.
Well Allen , what did you guys decide? :-)
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Fur,you might want to try shooting this gun and raising the fill pressure by 100 psi each fill till you see the fps drop.I have a 457 extreme and get my bell curve at 4700 psi.Your shoebox will do it.I have a older chain drive model and hits 4700 easily,the burst disc in the back of them are rated to 7000 psi and Brent said the extreme is good till 5000.do you have a inline pressure gauge to see when to cut it off?
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Fur,you might want to try shooting this gun and raising the fill pressure by 100 psi each fill till you see the fps drop.I have a 457 extreme and get my bell curve at 4700 psi.Your shoebox will do it.I have a older chain drive model and hits 4700 easily,the burst disc in the back of them are rated to 7000 psi and Brent said the extreme is good till 5000.do you have a inline pressure gauge to see when to cut it off?
Thanks for suggestion, I'm going to try for a bell curve at 4000 if possible. It's just not practical to shoot at 4500 psi for me.
And yes, I have a nice gauge to measure exact pressure.
Thanks for the all the feedback guys.. Stay tuned..
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I cannot seem to find my .308 strings but soon as it warms up a bit ill shoot some more. I will say that I use the light spring and only fill to about 3500. I also plan on tethering the gun soon to get some nice long distance shooting in.
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Tethering it should be lots of fun cause these guns are really accurate.I dont have the set up to tether my .457 but I have filled to 4400 after each shot and gotton 1.5 inch groups at 100 yards with the 245 gr maxi ball's.The Lee REALS aswell
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I'm more then sure sub MOA is possible with mine at 100. I would like to try to push it to 150 next.
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I was thinking the same thing.I can get a good hundred yard shot here at the house but thats it, want to take it some where I can stretch it out.I have a nikon with a bdc on it..if I lower the mag to a 7 power the 3rd dot is 153 yards so I wanna see how it does.Even at 150 it will be more powerful then my 909 at point blank range.
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Springs and more Springs!
Efunda.com has a cool spring rate calculator. I was off by 10% based on a vendor specs.
By the way, the "light" spring that came with my extreme is calculated to be ~11.5 LB/in
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/IMG_07111_zps0a1cb40e.jpg) (http://s258.photobucket.com/user/bginvestor/media/Rogue/IMG_07111_zps0a1cb40e.jpg.html)
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Life is good. ;-)
I'm already converging on the optimal pressure for the new spring selection.
I chose to start with a century spring #2894 which is ~7.7 lb/in. By the way, the stock "light" spring that came with the gun is estimated to be ~11.7 lb/in based on an on-line calculator.
So, this spring is pretty light.
Shooting a 109 grain HP ; using a chrono at 10 feet away.
Below, is a plot of velocity vs. number of shots as a function of initial pressure. ~3700 seems to be close to the bell curve. Not bad since I did not want to fill this gun close to 4000 psi. This pressure will allow me to shot a lot more, and still pack a punch!
I believe the next step will be to shoot the gun at the range and check accuracy from 3650 to 3750 psi fills...
I'm up to ~.7 FPE/cuin. much, much better.
(http://i258.photobucket.com/albums/hh270/bginvestor/extreme_pic_zps2bda0e81.png) (http://s258.photobucket.com/user/bginvestor/media/extreme_pic_zps2bda0e81.png.html)
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With your fills to 3750, your total ES is only about 24 fps or less.... I would suggest you try filling the gun to 4000 with that spring, you may be able to get 5 shots within a 4% ES.... Considering you are well over 1000 fps, that 0.7 FPE/CI isn't all that bad.... A heavier bullet to drop the velocity into the mid 900s will increase the efficiency even further.... I would look for something in the 140-150 gr. range....
Bob
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With your fills to 3750, your total ES is only about 24 fps or less.... I would suggest you try filling the gun to 4000 with that spring, you may be able to get 5 shots within a 4% ES.... Considering you are well over 1000 fps, that 0.7 FPE/CI isn't all that bad.... A heavier bullet to drop the velocity into the mid 900s will increase the efficiency even further.... I would look for something in the 140-150 gr. range....
Bob
Thanks Bob...
You know what surprised me, the chrono numbers shooting in the morning around 65 f was about 50 to 70 fps slower than shooting in the afternoon at 85 F..
I have ideas, but I wish I knew the 1st order effect.
The numbers presented above were during the afternoon session. Same bullets, same chrono, same everything..
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Sound like the lube on the hammer is thinning out at higher temps....
Bob
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Air Density
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How is the air density going to affect the velocity being produced by a shot of air that has already been compressed to 300 bar?....
Bob
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PV=nRT maybe? Keep everything constant but increase temperature, and the pressure rises enough to account for some change in energy. 60 fps seems a lot though, but it's part of it I'm guessing.
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Actually, the way the gun is tuned now, increasing the pressure will reduce the velocity.... Changing the temperature in a PCP doesn't affect the velocity in any significant way, but it will reduce the shot count.... The "T" in your formula is absolute temperature (Kelvin or Rankine) and a 60*F change in temperature will only change the pressure 10%....
Bob
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Changing the temperature in a PCP doesn't affect the velocity in any significant way, but it will reduce the shot count....
Correct about the absolute scale.
Interestingly, there have been some pretty thorough postings by people using guns much like this one (The Haley .257 and another Extreme .308 I believe) who have noticed speed changes with changing pressure. Unrepentantsinner wrote about this on another forum, and so did Cricket (both heavy-duty big-bore guys).
EDIT: here is the thread where somebody else shooting an Extreme .308 noticed velocity changes with temperature, and so did someone shooting a Haley .257
http://www.network54.com/Forum/79537/thread/1366590422/Some+observations+of+temperture+and+PCP%27s (http://www.network54.com/Forum/79537/thread/1366590422/Some+observations+of+temperture+and+PCP%27s)
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I would suggest the most likely cause is changing hammer velocity due to viscosity changes in the lube.... on hammer or spring.... or some secondary reason like sear friction....
Bob
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Just posting again in case this helps... here is the thread where two other different people: shooting an Extreme .308 and a Haley .257 noticed significant velocity changes with ambient temperature.
http://www.network54.com/Forum/79537/thread/1366590422/Some+observations+of+temperture+and+PCP%27s (http://www.network54.com/Forum/79537/thread/1366590422/Some+observations+of+temperture+and+PCP%27s)
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I'm off to the range right now, but I'm going to dig into this further. In the afternoon, the cast bullets were warm/slightly hot to the touch, in the morning, cold. I was going to check for CTE differences.
Just a thought for the moment, maybe not even worth writing about..
The spread was 45 to 70 fps depending on pressure fill and variability.
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Actually, the way the gun is tuned now, increasing the pressure will reduce the velocity.... Changing the temperature in a PCP doesn't affect the velocity in any significant way, but it will reduce the shot count.... The "T" in your formula is absolute temperature (Kelvin or Rankine) and a 60*F change in temperature will only change the pressure 10%....
Bob
I didn't fill the gun cold and shoot the gun hot.
I filled the gun to the EXACT pressure when the gun was cold and hot.
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Even more reason for the velocity change to be due to hammer effects....
Bob
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Even more reason for the velocity change to be due to hammer effects....
Bob
I guess we'll find out sooner or later what the major contributing factors are. Not to hijack the thread though, it does catch my interest what you say about "hammer effects".
Question: what is a short list of things (polishing, lube, etc) that you would suggest specifically to be done to a PCP hammer (the common cylindrical type that slides through the breech pushed by the spring) - to improve performance?
I've avoided any lube on my hammer due to worries about o-ring contamination and/or potentially explosive mixtures - but is there any you would recommend? What about polishing? (I polished my hammer with fine-grit sandpaper, and didn't really notice much effect - so maybe I did it wrong).
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I would recommend a dry graphite or moly coating on your hammer. Brownells sells a 2 part moly coating system that works great.
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I'm off to the range right now, but I'm going to dig into this further. In the afternoon, the cast bullets were warm/slightly hot to the touch, in the morning, cold. I was going to check for CTE differences.
Just a thought for the moment, maybe not even worth writing about..
The spread was 45 to 70 fps depending on pressure fill and variability.
Well, I did a quick hand calc, not reasonable that it's a CTE effect. Based on diameter, I calculated a thermal growth of almost 2/10 of a mil for a 35 F delta for lead.
I was just curious if the bullet sealed better, that the velocity could increase. I don't think so anymore..
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I would recommend a dry graphite or moly coating on your hammer. Brownells sells a 2 part moly coating system that works great.
Thanks for the info by the way...
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Just for the record, Extreme airguns recommends "liquid wrench chain lube" for hammer and orings.
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100 yard accuracy testing results... 3800 psi w 16x Vortex
I do not have a regulator yet, so I am at the mercy of the bell curve.
I did some testing at 100 yards using the .309 lee 115 grain FP mold. This was the same mold that was used to make my hollow point version discussed above.
I shot five strings (3 total shots for each string). I would have shot more, but my 8 year old was getting tired.
The chrono was measuring velocities at 975 , 987, 974 , for the first three shots respectively. Note , the high velocity for the 2nd shot.
Anyway, I will report the best 4 out of 5 strings. If the Olympics can throw out scores, we can't I?
The bottom line, the gun shot consistently . The second shot was always higher.
Center to center for all three shots
1 2.05"
2 2.4"
3 2.0"
4 threw out
5 3"
Ctc for the 1st and third shot
1 .53"
2 .59
3 .56"
4 threw out
5 .59
For a added bonus, I shot one string with the HP's. The group for all three was 1.19"
This is not sugar coating anything, just reporting raw data from today"s shoot.
Pretty happy so far, the gun has a lot of potential and shooting consistently.
I'm going to be working on the bell curve.
This is really a hunting gun for me. If I wanted to plink a lot , I should really get a regulator for exact pressure every time.
Maybe I'll tune the gun for consistent shots for the first and second. A back up shot with slightly lower psi?
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A 13 fps spread (~1.5%) should be virtually unnoticeable at 100 yards.... certainly not 1.5" higher than the other two.... Your 2" groups at 100 yards are pretty decent for cast bullets, IMO.... Using a BC of 0.17, Chairgun give a vertical POI change of only 0.50" between 974 fps and 987 at 100 yards....
Bob
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A 13 fps spread (~1.5%) should be virtually unnoticeable at 100 yards.... certainly not 1.5" higher than the other two.... Your 2" groups at 100 yards are pretty decent for cast bullets, IMO.... Using a BC of 0.17, Chairgun give a vertical POI change of only 0.50" between 974 fps and 987 at 100 yards....
Bob
Hi Bob,
Thanks for keeping me honest! The velocities reported was done before shooting these strings, so I actually don't know the exact velocities for these groups...
The bullet locations seemed to be consistent . One was higher and slightly right, while the others were tightly grouped.
Anyway, much more shooting necessary to define averages. I plan to post more data..
Also, I haven't done any experimentation on any sizing, and lubes yet.
This gun is a blast to shoot!
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My guess would be barrel harmonics.... If the barrel is travelling lower left to upper right as it oscillates, and the bullet is exiting more to the upper right of the swing at 987 fps than it is at 974-5 fps you would get exactly what you describe.... An inch of oscillation at 100 yards is only maybe 0.007" at the muzzle.... A small muzzle weight, or slightly different barrel band tension or bedding might be all it takes to change the timing of the arc.... The ideal situation is for the bullet to be exiting when the barrel pauses and reverses direction at the end of a vibration.... That way, even rather large differences in velocity won't print to different POI....
When reloading for a .222 Remington CF many years ago, as I increased the velocity I could watch the group string out from 8 o'clock to 2 o'clock at middle velocities, and then shrink at the 8 o'clock position at around 3000 fps and at the 2 o'clock position at around 3400 fps.... Trying to get a load to shoot at 3200 fps was useless.... 2800 fps was also useless, and at 3500 you could see the groups starting to track down and left again.... The groups at 8 o'clock (3000 fps) and 2 o'clock (3400 fps) were nearly 3 inches apart, but easily covered with a dime.....
Bob
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The problem I have with shooting very tight groups with my Extreme is the trigger. Timney are just not 'target' triggers. Now if I could get mine down to a pound or less even my groups would tighten up big time !!
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Any thoughts on lock time with respect to accuracy on the big bores? I can consistently shoot one ragged hole at 50 yards with my Extreme 45 but wonder how much better that would become if there wasn't a long interval between trigger sear disengagement and the valve opening. I struggled a long time with consistent hold and grip with this gun especially after shooting my CZ 204 with a set trigger. I have to believe that if the lock time on the Extreme was the same as the CZ that most of the bullets would print one clean hole. Just curious.
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Any thoughts on lock time with respect to accuracy on the big bores? I can consistently shoot one ragged hole at 50 yards with my Extreme 45 but wonder how much better that would become if there wasn't a long interval between trigger sear disengagement and the valve opening. I struggled a long time with consistent hold and grip with this gun especially after shooting my CZ 204 with a set trigger. I have to believe that if the lock time on the Extreme was the same as the CZ that most of the bullets would print one clean hole. Just curious.
Yup, if the cross hairs change from the time the sear disingages and puffs air, accuracy will suffer. The hammer is a big mass too! This suggests a nice firm set into the shoulder so the inertia of the hammer minimizes twist...
Ray, is that what you do? Currently, I'm setting the gun on bean bags front and back. Manny once said that he got better accuracy w/ the Evanix by not using a bag in the back since the bullet was moving slower..
Cheers..
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The problem I have with shooting very tight groups with my Extreme is the trigger. Timney are just not 'target' triggers. Now if I could get mine down to a pound or less even my groups would tighten up big time !!
Yup, lighter trigger will definitely help. I built a custom 1022 with a nice 1.5 lb trigger recently. Makes a difference.
By the way, I think the timney trigger is adjustable; however, I'm not messing with it!
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My guess would be barrel harmonics.... If the barrel is travelling lower left to upper right as it oscillates, and the bullet is exiting more to the upper right of the swing at 987 fps than it is at 974-5 fps you would get exactly what you describe.... An inch of oscillation at 100 yards is only maybe 0.007" at the muzzle.... A small muzzle weight, or slightly different barrel band tension or bedding might be all it takes to change the timing of the arc.... The ideal situation is for the bullet to be exiting when the barrel pauses and reverses direction at the end of a vibration.... That way, even rather large differences in velocity won't print to different POI....
When reloading for a .222 Remington CF many years ago, as I increased the velocity I could watch the group string out from 8 o'clock to 2 o'clock at middle velocities, and then shrink at the 8 o'clock position at around 3000 fps and at the 2 o'clock position at around 3400 fps.... Trying to get a load to shoot at 3200 fps was useless.... 2800 fps was also useless, and at 3500 you could see the groups starting to track down and left again.... The groups at 8 o'clock (3000 fps) and 2 o'clock (3400 fps) were nearly 3 inches apart, but easily covered with a dime.....
Bob
I agree.. maybe one adjustment could be bolt preload attaching stock to receiver. Maybe the tank compressing in the stock would preload the barrel band ?
By the way, does anyone know if the barrel band allows the barrel to slide? Looks like the band is firm on the barrel.
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I'm not a fan of having both the barrel and air reservoir locked solidly into the same barrel band.... I've seen too many cases of the reservoir changing length with pressure and bending the barrel up or down as it does so.... I usually use an O-ring to mount the barrel inside the band....
Bob
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A loose barrel band reminds me of the night mares that I had with my Marauder. It was designed to float but needed constant adjustment as it seemed to touch at some point after a few days of use. I believe that the Extreme is dead tight. My AA S510 is also tight and unbelievably accurate.
Love the Timney trigger on the Extreme. Never messed with it as it was so crisp and just about right for me. Do not have a trigger pull gage so not sure where it is set.
I have tried both a firm and loose shoulder hold as well as with the fore piece. I seem to get just as good of groups with my caldwell rear bag and front Rock rest with just a casual hold on the gun both front and rear allowing it to float a bit. Other guys like it tight.
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They come set at about 4 poundish according to Brent. Most of my target guns run from 4 oz to 13 oz at the heaviest. Allan told me once he would not advise taking the timney under 2 pounds for safety reasons.
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Dad came up for a visit; pictured here shooting the extreme . I switched vortex scopes with a better reticle.
After sighting in , he shot a .57" ctc 3 shot group at 50 yards. Not tethered/115 g FP/7.7 spring/3850 psi
Shooting great. At 100 yards, the 3rd hold over is almost perfect.
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/IMG_07161_zps6fb44d59.jpg) (http://s258.photobucket.com/user/bginvestor/media/Rogue/IMG_07161_zps6fb44d59.jpg.html)
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Looks like great fun. I always enjoy the chance to do something fun with Dad.
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Shot a coyote with the extreme!
video , click here..
http://youtu.be/vCPWQgl7VXk (http://youtu.be/vCPWQgl7VXk)
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/IMG_0717_zps24273782.jpg) (http://s258.photobucket.com/user/bginvestor/media/Rogue/IMG_0717_zps24273782.jpg.html)
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Nice Yote! Good shooting.
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One down and how many more to go :D? Nice shooting would have love to see the kill on vid yet I know I have missed or lost many shots farting around with a cam
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One down and how many more to go :D? Nice shooting would have love to see the kill on vid yet I know I have missed or lost many shots farting around with a cam
I have a Contour cam that's mounted to the shotgun and it works pretty well .. just flip a switch and forget about it..
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I am planning to go to the range later this week.. I'll be trying bullets that are sized and lubed. Oh yeah, going to try a bullet of my own design from an accurate mold. Its a FP. :P
Should be fun.
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/photo4_zpseff50600.jpg) (http://s258.photobucket.com/user/bginvestor/media/Rogue/photo4_zpseff50600.jpg.html)
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More 100 yard testing.. 3 shot groups No sugar coating..
I tested three types of bullets.
Lower left is my bullet design
Lower right unlubed /sized HP
Center is lubed/sized FP
Upper left is lubed/sized FP
Upper right is unlubed HP
I noticed after 20 shots my groups were opening up. I guess the manual is serious about cleaning barrel after 15 to 20 shots!
Early indications is that the gun likes a unsized bullet rather than a sized .308 bullet. Next step is to try a lubed unsized bullet.
Its nice to see that HP's are shooting slightly better than the FP since they are my hunting bullet.
(http://i258.photobucket.com/albums/hh270/bginvestor/IMG_0737_zps6deae45c.jpg) (http://s258.photobucket.com/user/bginvestor/media/IMG_0737_zps6deae45c.jpg.html)
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Good group on that unlubed, unsized HP.... My DAQ shot better with unsized bullets as well....
Bob
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Good group on that unlubed, unsized HP.... My DAQ shot better with unsized bullets as well....
Bob
Bob, my Extreme is more accurate at 100 yards than the Rogue was at 50 yards! lol
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That was a nice group on the upper right. You will have to clean a lot until you get it broken in. I have a Haley 257 that I
Could not get 15 shots before I had to clean it. You could see the buildup with a light. Then I started lubing my bullets
That helped a lot. It made it easier to clean also. To start with I had to use solvent to get all the lead out. I did not have
Near that problem with the two 45 calaber guns I have. I did end up fire lapping the barrel to get it smothed out. Now I
Can shoot 60 lubed bullets or more before I pull a patch trough.
People at the range are amazed that I shoot at 200 yards with this gun. I have a 6x6 metal targets I shoot at. I can see
Where it hits at that distance and I like to hear it ring.
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William....specifically how did you fire lap your Haley? I am ready to do my new Condor 257 and plan to use Roachcreeks recommendations by using only the higher 2 grits the 320 and 600 . Just very curious.
thanks Ray
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Hay Ray: roachcreek or charlie had the same rifle I do except he had a extra barrel with a faster twist to shoot
Heavier bullets. He has some good advise on three or more forums. Unfortunate he has gotten out of airguns.
I started out using jb bore paste with a tight patch. That did not get it done but it helped. Then I got the wheeler bore
Laping kit. I only used the 320 grit and 600.
15 shots with 320 grit. Clean after every 5 shots.
30 shots with 600 grit. Clean after every 5 shots.
That helped a lot. I ended up doing it again with 600 grit one more time.
40 shots with 600 grit clean after every 5 shots…
The good thing about my gun you can unscrew the barrel to clean it. No port whole to line up.
Ray I would shoot it first to see how it does.
Check out tofazou blogspot he has a 257 on air force set up that he was hitting coke can at
450 yards.
Roachcreek has the longest shot made with a air rifle. He shot a coke can at 600 yards.
He called it the pepsi challenge 600 on ytube.
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Hay Ray: roachcreek or charlie had the same rifle I do except he had a extra barrel with a faster twist to shoot
Heavier bullets. He has some good advise on three or more forums. Unfortunate he has gotten out of airguns.
I started out using jb bore paste with a tight patch. That did not get it done but it helped. Then I got the wheeler bore
Laping kit. I only used the 320 grit and 600.
15 shots with 320 grit. Clean after every 5 shots.
30 shots with 600 grit. Clean after every 5 shots.
That helped a lot. I ended up doing it again with 600 grit one more time.
40 shots with 600 grit clean after every 5 shots…
The good thing about my gun you can unscrew the barrel to clean it. No port whole to line up.
Ray I would shoot it first to see how it does.
Check out tofazou blogspot he has a 257 on air force set up that he was hitting coke can at
450 yards.
Roachcreek has the longest shot made with a air rifle. He shot a coke can at 600 yards.
He called it the pepsi challenge 600 on ytube.
Hi William, thanks for the info.. What's your favorite lube?
Oh yeah, I'm looking for .257 , wish I could find a haley
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Thanks for the info William. I put 5 slugs with 320 grit down the pipe, cleaned then 5 more. Then I did the same with 600 grit. Sounds like I may need to do it over again using twice as many. One thing I noticed is that when using soft cast slugs and rolling them on the steel plates they are reduced significantly in diameter so wonder if I need to use a harder slug that won't deform so much. When they get reduced in diameter I am sure there is much less scrubbing action in the bore. Will report more when I have time.
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Thanks for the info William. I put 5 slugs with 320 grit down the pipe, cleaned then 5 more. Then I did the same with 600 grit. Sounds like I may need to do it over again using twice as many. One thing I noticed is that when using soft cast slugs and rolling them on the steel plates they are reduced significantly in diameter so wonder if I need to use a harder slug that won't deform so much. When they get reduced in diameter I am sure there is much less scrubbing action in the bore. Will report more when I have time.
Please let us know your results!
It does make sense that more 600 grit is required to take out the scratches of the courser grit.
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Today I shot a coyote at 100 yards.. Hit it square in the chest , his legs stiffened, and tipped over..
Freakin awesome!
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My buddy shot my extreme last weekend and did real well at 100 yards..
He shot two 3 shot strings.
If taking ctc of the first , second, and third shots, the numbers are .35", .45", and 1.25". That's pretty good consistency.
If taking the aggregate (all), the group is estimated to be around 2.5" ctc.
This lend to do more velocity measurements yesterday. I wanted to fine tune my pressure for consistent velocity . I had been using 3800 psi.
The answer looks like 3775 psi for the 115 HP , no size, no lube.
See the graph below. Most shots are taken at 3700, 3750, 3775, and 3800 psi.
I noticed during the session that some bullets slid in very easy and some needed to decent push. I think its time to get serious and get very consistent lead in weight and diameter. I am thinking of maybe using a .309 die to smooth out any edges.
I got to say, I really love this gun. No leaks, works perfect, and is pretty darn accurate! I got the cleaning of the barrel down to a science. Lol
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/velocity_HP_zps6d1e306c.png) (http://s258.photobucket.com/user/bginvestor/media/Rogue/velocity_HP_zps6d1e306c.png.html)
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Had some more fun this morning...
This round, I cherry picked perfect bullets in .309 " in the 115 HP. In addition, I used the optimal velocity of 3775 psi that gave the most consistent velocity from testing..
The overall results at 50 yards were a little disappointing. I believe sizing down to .309" or form is the cause.
More testing will verify..
The pic below shows the grouping of the 1st, 2nd, and 3rd shots of each string. So, the group on the right is the first shots of three strings and so forth..
Results are 1.4", 1.16", and 1" ctc for the first thru third groups, respectively. If this was 100 , I would be happy, but it was at 50 yards.
I did recall that previous testing did not show as good for any sizing . The next step is to shoot with more unsized bullets.
Best group of the day was .55", worst was 1.8"
I noticed that's my first shot groups differently than the 2nd and 3rd.. I need to figure out if it's form or the pressure since it's killing the group size.
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/IMG_07651_zpsa0b4170c.jpg)
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I decided it was time to check out other mold designs..
I chose a spitzer bullet from RCBS. It stunk that I had to buy a $40 dollar handle for it. Lol
These puppies were coming out at an average of .313", so testing was done sized to .309". They are around a 130 grain bullet. Extreme's are known to shoot long heavy bullets. After receiving the mold, I decided to check the gyroscopic stability and it came in at ~1.1. Cutting it close , huh?
Shooting from 50 yards, this was the first couple of shots.. First one was the HP to confirm it was sited. The two grouped were the first couple of shots with these new bullets. I got very excited!
However, after more testing, I started grouping at 1" to 1.5" with four three shot groups... Not there yet! Did the barrel lead fast? Probably not, it was just a fluke based on my other groups.. They seem to fly good, no tumbling yet..
In any case, I need to do some more tweaks..
My plan is to up the velocity and resize .. It's going to be sweet if I get these beauties to fly well..
(http://i258.photobucket.com/albums/hh270/bginvestor/Rogue/IMG_07881_zps886b3c09.jpg) (http://s258.photobucket.com/user/bginvestor/media/Rogue/IMG_07881_zps886b3c09.jpg.html)
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At a SF = 1.1 you could have a problem at high altitude on a hot dry day.... low air density could tip the scales against you....
Bob
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At a SF = 1.1 you could have a problem at high altitude on a hot dry day.... low air density could tip the scales against you....
Bob
Right. .. Good thing that I live in the desert in lower altitude..
Does anyone know of a good machinist that can take a .308 sizing die and increase ? Thx
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Not that hard to do if you have a lathe and a Dremel.... I mounted my Dremel on the compound feed and set it at a few degrees to match the taper of the inside of the sizing die.... Using a 3/16" straight stone, like used for sharpening a chainsaw, I gradually opened up the hole until it sized a bullet to the size I wanted.... You have to go VERY slowly, just a fraction of a thou at a time....
Bob