Location: S.W. Pa.-- Heart in North Central Pa. mountains-
Posts: 2,508
Trimming Ackley cases
Been loading for my .243 Ackley for awhile now, and I've noticed that since the cases were new fireformed, the trim-to length hasn't changed much at all if any. I guess that's because of the nearly straight-sided casings that come from the Ackley design and proper die set-up. I'm reloading the same casings now for the 5th time, and although I check trim length on every one, the length hasn't changed. I'm impressed. Any other Ackley shooters out there have any comments??
I'm on my third reloading with Lapua brass with no trimming yet. Some are starting to get a hard bolt closure though...
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You are correct that straight-side, sharp-shouldered cases need little, if any, trimming. The brass doesn't flow much. But rounds like the 300 H&H are just the opposite. Even the 270 Win. stretches pretty badly...
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Location: S.W. Pa.-- Heart in North Central Pa. mountains-
Posts: 2,508
RE: Trimming Ackley cases
Quote:
ORIGINAL: eldeguello
You are correct that straight-side, sharp-shouldered cases need little, if any, trimming. The brass doesn't flow much. But rounds like the 300 H&H are just the opposite. Even the 270 Win. stretches pretty badly...
Yep.....The 300 H&H is the prime example of why a belt was needed. Not enough shoulder angle along with a relatively sharp body taper to headspace on properly....In effect, causes brass to flow forward much faster.
In my 22-250 AI, I seeon first firing the original case that it shrinks to fill the void where the shoulders and sides have not blown out. So to start out the case gets shorter. Usually after that I trim them once to make them uniform and never had to trim them again. To be honest I see that as a big plus beyond the additional 100-150 fps I get over standard loadings.
In my 22-250 AI, I seeon first firing the original case that it shrinks to fill the void where the shoulders and sides have not blown out. So to start out the case gets shorter. Usually after that I trim them once to make them uniform and never had to trim them again. To be honest I see that as a big plus beyond the additional 100-150 fps I get over standard loadings.
If your gaining over 2% in MV over a standard chamber by going AI, one of 2 things is going on, either you have a longer barrel or your shooting at higher pressure which isn't noticeable due to the tight chamber, and the minimal body taper, also alot of trimming is not really needed, I have a rem. 760 270 win (ya know the long tapered case with not much of a shoulder angle) that has had cases loaded over 1 dozen times without trimming. But the die is set to min. headspace for that chamber
of course the cases get shorter the first time around, AI cartridges are headspaced .004" shorter than standard rounds.
RR
I'm on my third reloading with Lapua brass with no trimming yet. Some are starting to get a hard bolt closure though...
Jeepkid, Set your die to bump the shoulder a little more. The tight bolt close is not because of the overall cartridge length. If your die is set to bump the shoulder back .001 to .002 you'll see the bolt closing a lot easier. If you don't have a headspace guage just bump the shoulder a little more each time and try to chamber it until it closes nice.
Trimming Ackley cases
