consistent OAL

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consistent OAL

Postby horseman » 11 Mar 2020 12

I may have found a way to help in OAL consistency on a/my progressive press. I say may have because I've only done this for the last 20 or so rounds I've done. I'm loading 45 acp +P ammunition 16 at a time looking for a specific FPS area (900-950) over a chrony so wanted to keep the OAL as consistent as possible to try and eliminate that as a cause for high ES. Necessary or not is not in question here. I was finding that when I'd go from seating a bullet in the bullet seating die to a specific length (using a Hornady bullet seating die) say 1.230 (actually what my target is) with that die just touching the case mouth plus just a bit. Then run the cartridge into another bullet seating die (Lee) to finish crimp, with bullet seating stem backed out, I could/did get 3 to 5 thousandths INCREASE from the 1.230 OAL target on a lot of the rounds. If the length increase was over three thou. I would set these aside and redo. So, on some of these (maybe all) the act of crimping after seating seemed it was/could cause an increase in OAL. Normally I wouldn't worry about these small numbers (except in CF rifle loading) but this was a test of sorts. I ended up setting up the SECOND bullet seating die as I would to seat and crimp in one operation with the same 1.230 OAL setting as the first die and it seemed to work. By setting the bullet seating stem in the "crimping" die to hold the bullet at the same 1.230 I had no increase in OAL. I could probably do the same thing by just using the one die and seating and crimping in one operation, but that would be much to simple and I would have had nothing to talk about here..... :lol:
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Re: consistent OAL

Postby Ohio3Wheels » 11 Mar 2020 12

I noticed much the same thing using a single stage press and a Lee FCD with 45 Colt, growing on crimp, went to a tapper crimp and lost the growth. I'm not sure the growth mattered in the Colt as some of the loads had SDs in the 1.* to 3 range, but that's in the bigger case so may apply to the ACP.

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Re: consistent OAL

Postby Macd » 11 Mar 2020 18

Good to hear you have found something that works for you.
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