GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Big Bore AirGun Gate => Topic started by: QVTom on September 06, 2015, 05:16:02 PM
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Doug Noble was kind enough to cast some 357, 110 gn. BBTS. If you haven't seen Doug's work, take a good look at the picture; the workmanship is quite amazing.
(http://i1147.photobucket.com/albums/o553/QVTOM/RainStorm/20150906_130626_zpsy7rfeamk.jpg)
First the Crony testing and hopefully accuracy testing later today if time permits.
1041 - 3600 psi
1053
1063
1048
1040
1018 - 2700
Wow! Thats a ES of 23 for the first 5 shots :) A average velocity of 1049 for an average 269 FPE. ES for the 5 shots is 2.2%
Next comes the 85 yard accuracy testing.
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Looking good, those are beautiful bullets.
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Beautiful bullets, indeed....
Bob
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Great job Tom! That is a very impressive ES!!! Bet your cheeks hurt from smiling so big!! ;D For the record....I haven't seen a BBT I didn't like yet!
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Very nice Tom I am loving the numbers
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Maybe i'm pushing them too fast or the gun just doesn't like them which is a shame because the ES is so good. Results are results so here they are. I call this group at 85 yards not worthy of measurement LOL.
(http://i1147.photobucket.com/albums/o553/QVTOM/RainStorm/20150906_163524_zpsgfmir63p.jpg)
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Maybe i'm pushing them too fast or the gun just doesn't like them which is a shame because the ES is so good. Results are results so here they are. I call this group at 85 yards not worthy of measurement LOL.
(http://i1147.photobucket.com/albums/o553/QVTOM/RainStorm/20150906_163524_zpsgfmir63p.jpg)
Tom turn down to 960fps
also the very best way to determine is to video the shots then review in slo-mo and see exactly what the projectile is doing.
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Not much sense in shooting a bullet that light if I need to turn them down that far. I was looking for flat shooting but the 110gn is not the answer.
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Those 125gr are still my favorite of all the ones I've used.
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Wish the shots were number Tom. Could possibly tell more. Have you lapped the barrel yet?
What lube are you using? I had similar results with the .257, then on RoachCreek's (unrepentedsinner), advice, I lapped the barrel, and went to 10 wt. silicon shock oil. Made a HUGE differnence.
We have also noticed that the barrels tend to break in, and shoot much better. Was the barrel leaded in before the accuracy test? Mine takes 5-6 after a good cleaning. Before break-in, it could take up to 10-15, which was terrible as the new barrel would lead with in 25 shots, and have to be cleaned again.
It now will go 150-200 before needing cleaning when using lube, and still 75 or more without it. But not as accurate without the lube.
Knife
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I would slow down to see if the groups improve 1050 is real fast. You could dial down 1000 then 950. The more you learn about the characteristics of your gun the better.
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Wish the shots were number Tom. Could possibly tell more. Have you lapped the barrel yet?
What lube are you using? I had similar results with the .257, then on RoachCreek's (unrepentedsinner), advice, I lapped the barrel, and went to 10 wt. silicon shock oil. Made a HUGE differnence.
We have also noticed that the barrels tend to break in, and shoot much better. Was the barrel leaded in before the accuracy test? Mine takes 5-6 after a good cleaning. Before break-in, it could take up to 10-15, which was terrible as the new barrel would lead with in 25 shots, and have to be cleaned again.
It now will go 150-200 before needing cleaning when using lube, and still 75 or more without it. But not as accurate without the lube.
Knife
I have no problem holding .5" groups at that range with my 125 and 139 gn slugs as well as the 140 gn I recently had a mold made. I shot a near perfect control group right after the BBT to confirm, the gun just doesn't like them. I could bring them down to 950 but that kind of defeats the purpose, I might as well shoot the 125 that will shoot under 2" at 200 yards. FYI, I never lube my slugs although they have a trace amount of sizing wax on them.
With a group like that I doubt there is much that will bring it inline. Just a bad match.
Tom
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It would still be interesting to see if you can make them group at 950ish fps as I've also had problems in getting those BBTs to group in my gun. Personally I'd love to find a "heavy" bullet that fits the Evanix magazine and groups well.
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I would agree, Tom, a bad match at that velocity.... and not much point in slowing it down as you have accurate bullets going slower anyway.... Not everything works in every gun, unfortunately....
Bob
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Hello Tom, you might try upping the brinell hardness of your bullets, just a thought...Allen
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Those results are very similar to what Cedric has produced with my swaged .257 BBT. I'm working on a sleeker version with longer ogive. I have a gut feeling that at these higher speeds, the CG needs to be a hair further back and a longer ogive nose will give us that. Then we have to increase the OAL length to get the weight back. That will cause us to run the ragged edge of the twist stability ranges of these barrels. I agree with Bob on the thought that the calculators are over compensating for the rebated BT. I'd like to see if that bullet would improve is groups with a HP. If so, that would lend to the theory that the CG needs to be further back. I had been thinking that it was due to such a large bearing surface but once I really put my head to that, it just doesn't make since. Although the huge bearing surface does make them WAY more difficult to chamber.
BTW, those are gorgeous bullets
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Hello Tom, you might try upping the brinell hardness of your bullets, just a thought...Allen
Allen,
Thats EXACTLY what made my 7mm BBTs perform even better.
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Tom,
Just for info purposes in your gun, which size shot better? The ones i sized (.3572") for you or the size doug sized (.3573") and i think i made you some .3578" or .360" Can't really remember.
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Those results are very similar to what Cedric has produced with my swaged .257 BBT. I'm working on a sleeker version with longer ogive. I have a gut feeling that at these higher speeds, the CG needs to be a hair further back and a longer ogive nose will give us that. Then we have to increase the OAL length to get the weight back. That will cause us to run the ragged edge of the twist stability ranges of these barrels. I agree with Bob on the thought that the calculators are over compensating for the rebated BT. I'd like to see if that bullet would improve is groups with a HP. If so, that would lend to the theory that the CG needs to be further back. I had been thinking that it was due to such a large bearing surface but once I really put my head to that, it just doesn't make since. Although the huge bearing surface does make them WAY more difficult to chamber.
BTW, those are gorgeous bullets
Bill, I think you may be on to something in terms of CG. The two best shooting bullets for this gun are John Cripe's Swaged 125 and 139 FPs, they both have a 3/4 radius nose with a rather short shank and very short boattail. The CG is considerably further back than the 110 BBT.
Going back to my 45 ACP days there were only two designs of bullets target shooters used. The Keith and hollow points in the 185-200 gn range. Both of the designs have a significantly rearward CG and both are know to shoot extremely well.
One more data point which is somewhat subjective because I didn't do any real serious testing just came away with an impression. Cedric made some HP boatails from a Lyman mold known as the Devastator. The first batch I received shot reasonable well, just over an inch at 85 IIRC. Cedric not being happy with the performance had the HP pin shortened to change the CG, when I shot the revised version I felt they did not perform as well. I have no hard data on this one, just my instinct.
Tom
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Tom,
Just for info purposes in your gun, which size shot better? The ones i sized (.3572") for you or the size doug sized (.3573") and i think i made you some .3578" or .360" Can't really remember.
I can't remember either LOL. I thought the first BBTs you gave me were heavier than 110 gn. Anyhow I don't think there were enough of them to tell. I do remember a Keith bullet in that gift tupperware (the only tupperware party worth having :)) that shot well. Maybe we should revisit that one for a lightweight alternative.
As for size and hardness, I've shot diameters from 3570 to 3585 and not seen any significant difference in groups. The odd performer was the Hunter's Supply 127 gn FP which measured from 3575 to 35785 and are made with 5% tin and had some serious distortion of the drive bands, maybe a design to evaluate further.
Tom
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Ever consider barrel harmonics?
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Tom,
Just for info purposes in your gun, which size shot better? The ones i sized (.3572") for you or the size doug sized (.3573") and i think i made you some .3578" or .360" Can't really remember.
I can't remember either LOL. I thought the first BBTs you gave me were heavier than 110 gn. Anyhow I don't think there were enough of them to tell. I do remember a Keith bullet in that gift tupperware (the only tupperware party worth having :)) that shot well. Maybe we should revisit that one for a lightweight alternative.
As for size and hardness, I've shot diameters from 3570 to 3585 and not seen any significant difference in groups. The odd performer was the Hunter's Supply 127 gn FP which measured from 3575 to 35785 and are made with 5% tin and had some serious distortion of the drive bands, maybe a design to evaluate further.
Tom
GIFT Tupperware.....lol..........love it!
Yeah, that was the 110 gr LEE SWC. I love those things myself. They are about as accurate as JSB in my gun. I shoot them at 870 FPS though out of the 16" twist TJ. I also shot them in the OEM Recluse barrel at .358 and 1-20" twist and they were darned accurate there too. The JSB's were the same. Accurate in both barrel that are completely different.
I have a bunch of those cast. I CAN HOOK YA UP!
The BBT's also have always been 110 grs.
My buddy is working on a new pin for that Devastator also. So we shall see