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Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by critterskinner, Nov 30, 2010.
Which is better ballistic wise?
I heard some rumblings that cheytac`might be going out of business???
Don't know how true that is.
Even if Cheytac did go bellyup components would still be available through Jamison and other sources.
IMO,The extra FPS gained isn't worth the hassle of fire forming.
Not that I know much about either, but what I see I really love the 375 snipetac, maybe one of these days one will grace my gun room. If I were to win the lottery I am sure I would be on the FBI's most watched list for all the firearm power I would have.
There is not much gain in velocity between the standard case and the improved case, but there is much to gain in terms of efficiency, that far outweigh the "hassle" of fireforming if you start with the standard .375 or the .408 case.
I'm curious how so? No disrespect,just wondering.I only say this because I have a regular 375CT.The problem I find with the cartridge is the lack of suitable modern powders giving proper load density to achieve proper "efficiency".Even a max load of Retumbo (134 grains) behind a 350 Jamison is 1/4" below the shoulder.I'm assuming load density would be a worse problem on the improved case. Maybe I'm wrong?
I've had slight hangfires with R-25 which I feel is too fast of a powder for the 375CT and have had hangfires with some of the really slow 50 BMG powders.No problems with Retumbo,US-869(very temp sensitive),AA8700 which is no longer available.I think the 375CT case is already on the very edge of what a large rifle magnum primer will reliably ignite as is,let alone an improved version.
I enjoy wildcat and/or AI type cartridges myself.Of course the other cartridges are standard sized,6mmART40,30-375R,6x47L and others I've owned over the years.With them it's no problem finding the perfect powder and yes they are very efficient.
No disrespect taken at all...
Shot the .375-.408 quite a bit until I settled on the .338-.408. All my rifles are chambered for the improved cases. I never had an issue with load density in the .375. Retumbo was my powder of choice with the 350 SMK and the 215's. Never had any issues with hang fires with either the Retumbo or H50BMG. Most rifles were single digit ES.
Powder of choice with the .338-.408 improved case is H50BMG. I can fill the case with more powder and pick up the velocity, at the cost of accuracy. Personally, I have not had any issues with load density in either case.
I have never had any hangfire issues with my 375 Allen Magnum which is just a lightly more extreme version of the Snipertac. In reality, performance wise, very similiar, just a bit different case design.
I have used up to 146.0 gr Retumbo and as low as 135.0 gr retumbo under the 350 gr SMK and never had any hangfiring. From velocities from 3100 up to +3300 fps.
Perhaps your hangfires are more from the increased body taper and shallower shoulder angle and maybe a bit to much bump on the shoulder of the case?
It has never been a problem to get low teens for extreme spreads with any of my 375 AMs but as Joel mentioned, they are very consistant.
I considered the fireforming issue when I released my 375 AM as well as my 338 AM and that is why I had Jamison make me my own headstamped brass and I offer fully formed cases for customers to eliminate that concern and barrel wear.
If you look at the factory load specs for the 375 Chey Tac, there is much more to be had with the Improved versions but that is mainly because Chey tac loads their ammo rather mildly by most standards and the ST and my AM are loaded to top working loads.
With my accuracy load, 144.0 gr Retumbo under the 350 gr SMK, I am running around a 95% load density. Still air in the case but plenty full and no chance of powder fracturing.
I am surpised you had hangfire issues with H-50BMG but not with US869 or AA8700 which are much more difficult to ignite then 50 BMG.
Yep no problems here with my 375CT either.... maybe you got a bad batch of primers or a bit of moisture from somewhere or something???
And for the OP, the 375CT already pushes 350gr @ 3200fps from a 34"bbl... i dont really see the need for anymore ballistic performance than this!
All comes down to the fire forming brass issue and could you be bothered or not...
Fiftydriver and groper,
Thanks for the info.I haven't tried H50BMG yet.The powders I used were IIRC 5010 and one of the Vit 50 cal powders.This was three years ago when I tried them and it was a short lived experiment.
I had minimum shoulder bump on the cases,.0015. Retumbo has worked fine with no hangfires.R-25 had been the main culprit with the hangfires.It was quite a process finding the right powder and projectiles back then.I got the gun right when Lost river went out of business,arrrg.For some reason I tried Retumbo last???
Fifty,That's great you have your own improved 375AM and 338AM brass already formed if wanted.Great idea!
If your getting low ES/SD and good accuracy then enough said.Can't argue with success!
Gentlemen, in this discussion you mention fire forming brass. If you don't mind educating me, which of these two rounds requires being fire-formed and which does not? I am looking to build my "dream rifle" and I am debating between several calibers including the different .338's, .378's, and the .408. I am also concerned with the lack of commercially available ammo with the Snipetac.