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Chasing speed or accuracy?

1121 Views 16 Replies 8 Participants Last post by  Thatguyshm
So with the 120gr SSTs, I've been testing my different on hand powders and noticed that 322 and 335 would not work. I next went on to Re10x and my lowest powder charge of 26.8 ended up putting five in one hole, possibly the best group the rifle has ever shot.

Avg 2419
SD 3.0
ES of 7

Amazing numbers besides the velocity. I am waiting on a jug of AA2200 to get here to test out.

I shot two more groups in .3gr increments, 27.4 looked acceptable, about an inch, may have thrown two shots. Still getting used to the upgrades I put in my rifle. Even then the SD was 9.3 and ES was 34 avg of 2470. All shot in new SSA brass with CCI 41s.

Dunno which way to go here.
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Oh yeah, upper was built early 2010, stag upper, Bison armory 18" barrel, specII chamber, Troy 11" alpha rail. Just put a new PRI 6.8 muzzle brake on it. Lower is a newer Anderson with matching LPK, just upgraded the trigger to a geissle SSA two stage, Luth-AR mba-1 fixed stock, Endine hydraulic buffer and hogue grip.
Aa2200

My 18" ARP with 27.5gr of AA2200 using 120 SSTs yields 2550 fps.
My 18" ARP with 27.5gr of AA2200 using 120 SSTs yields 2550 fps.
I've got an eight pounder en route, just waiting for it to get here. Next build will have a 20" ARP, just gotta get the stuff ordered.

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What do you mean by 322 and 335 'didn't work'?
What do you mean by 322 and 335 'didn't work'?
I couldn't get any kind of accuracy out of H322, and my H335 gave me 2366 fps and a bit over an inch. That was at 29.0. ES and SD were single digits just no speed.

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I couldn't get any kind of accuracy out of H322, and my H335 gave me 2366 fps and a bit over an inch. That was at 29.0. ES and SD were single digits just no speed.

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The first powder I used in 6.8 was H322 and I was not happy with it either. Accuracy was mediocre at best, and it always seemed like it ran hot temp wise. Three rounds and the barrel would be hot enough to blister your skin. H335 is too slow in my opinion for the 6.8. 2200 is almost perfect with 100 gr. on up. My go-to was 28.5 with the 110 HPBT w/c Hornady and #34 primer (I used Remington brass with LP). It ran relatively cool, and was scary accurate in my 18" ARP 5R barrel.
I have had good luck with H322 in some loads and not so much in others. 100ABs with 30gr of H322 were pretty accurate. 100GMX I haven't had the best of luck wih H322 so trying some AA2200 next.
All shot in new SSA brass with CCI 41s.
Resized brass has expanded to fit your chamber which changes your case capacity. Expect you grouping to change and you may need to do another round of load develop development.
335 is too slow for short barrels, I use it in my 24" 6.8 with good results though.

Once you get a decent group, try it again in fire formed brass, then adjust seating depth to fine tune your groups, may have to window a mag to get the seating depth that groups best.

-Alexander
Speed vs accuracy really depends on what the intended use is. If putting tiny groups on paper is the goal then obviously the most accurate loading would be preferred. If hunting out to 3-400yds then speed is more important to an extent. If a particular load will reliably group within the kill zone area of whatever game I'm hunting and has a significant velocity advantage over a 1" group, I'll hunt with the faster load.
I couldn't get any kind of accuracy out of H322, and my H335 gave me 2366 fps and a bit over an inch. That was at 29.0. ES and SD were single digits just no speed.

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Got it, thanks. Thought maybe it was a functioning problem or something.
Resized brass has expanded to fit your chamber which changes your case capacity. Expect you grouping to change and you may need to do another round of load develop development.
We'll find out today. I'll pop a spent primer in a new piece and then one in the processed and resized brass, throw some water in and see what the variation is. I don't see it being much over .1~.2gr if anything. Interesting experiment though.

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335 is too slow for short barrels, I use it in my 24" 6.8 with good results though.

Once you get a decent group, try it again in fire formed brass, then adjust seating depth to fine tune your groups, may have to window a mag to get the seating depth that groups best.

-Alexander
Do you have the link of the photos where the mags were windowed? I've been searching and can't seem to find them.

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Speed vs accuracy really depends on what the intended use is. If putting tiny groups on paper is the goal then obviously the most accurate loading would be preferred. If hunting out to 3-400yds then speed is more important to an extent. If a particular load will reliably group within the kill zone area of whatever game I'm hunting and has a significant velocity advantage over a 1" group, I'll hunt with the faster load.
That's why I've stopped shooting the 120's for now. I'll pick them up again when I have the 2200. 2470fps isn't terrible but I'd prefer to be over 2500fps.

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I'll pop a spent primer in a new piece and then one in the processed and resized brass, throw some water in and see what the variation is. I don't see it being much over .1~.2gr if anything. Interesting experiment though.
Any change in the brass, even small, affects a load. Besides the case capacity, the brass also becomes worked hardened so that it expands differently and neck tension will also be different. Are you bumping your shoulder back only 0.003"? ... My .270 likes Remington brass. I sort new brass by weight. Same brass but one weight range gives me 0.5 MOA and another 1.0 MOA. I don't sort by weight with my 6.8 because I don't shoot past 300 yards with it.

Do you have the link of the photos where the mags were windowed?
http://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs
Any change in the brass, even small, affects a load. Besides the case capacity, the brass also becomes worked hardened so that it expands differently and neck tension will also be different. Are you bumping your shoulder back only 0.003"? ... My .270 likes Remington brass. I sort new brass by weight. Same brass but one weight range gives me 0.5 MOA and another 1.0 MOA. I don't sort by weight with my 6.8 because I don't shoot past 300 yards with it.
I understand and agree am that, understand metallurgy's basic concepts as it pertains to brass cases, and don't see that there will be enough of a change in the same batch of brass, on the same firing number, without the use PE stress gauge testing, to be considered a large enough of a factor to record. Yes I keep track of number of times fired, how often I anneal, all those numbers, but in this cartridge I think the variables of the rifles movement while shooting and environmentals to effect POI more than the slight changes to the brass.

I do bump the shoulder, and currently I am loading everything single stage on my co-ax, run out is right at .001" at most.

I load precision ammo for many rifles, 300wm, 6mm br, 338-06, 257wby, all sorts of ammo I can easily get under .75 moa, the 6br is pretty standard in the 3s, if I do my part I can hit mid low 2s.

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