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Maximum and Minimum cartridge case OAL
Posted: Wed Sep 18, 2024 8:35 am
by Mauserbill
Hello
Reloading manuals and data sheets always give a maximum OAL length, but what about the Minimum value ??
Re: Maximum and Minimum cartridge case OAL
Posted: Wed Sep 18, 2024 8:51 am
by billgatese30
They usually give a trim length which I would treat as the minimum. Any less and you are sacrificing grip on the projectile and possibly difficulty in sealing the neck against the chamber during the pressure spike
Re: Maximum and Minimum cartridge case OAL
Posted: Wed Sep 18, 2024 10:50 am
by rox
Look at the relevant SAAMI or CIP drawing for the cartridge to find the dimensions and tolerances. For example, SAAMI .308 Win shows 2.015" - 0.020", so the minimum is 1.995". The 'trim' length often found in manuals is essentially an arbitrary value somewhere in the middle of the range which gives the best chance of hitting the tolerance window.
Find the SAAMI standards here (e.g. SAAMI Z299.4 for centrefire rifle)
https://saami.org/technical-information ... standards/
CIP drawings are here:
https://bobp.cip-bobp.org/en/tdcc_public