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The SAAMI standard is 1.995" to 2.015". The military standard is 2.000" to 2.015". However, some service rifle match shooters used to trim down to below either number to around 1.980". This was done with the idea they would have to retire the brass before they had to trim it again. In self-loaders brass life is not usually high, due to the hard extraction, 4 to 6 reloads being typical. At an average of 0.005" growth per load cycle, that works out about right. Also, if you have a manual trimmer only, while this over-trimming practice doesn't save you any actual cutting time, it does save you having to remount the case for trimming more than once.
The main thing is that whatever trim length you chose, you check to be sure it doesn't adversely affect accuracy in your gun. With some short bearing surface bullets like the 155 grain Sierra Palma bullet, that over-trimming practice could force you to seat deeper than your gun likes best, just to help the case hang onto the bullet. Or, you could just stick with one of the published limits, above.
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Last edited by Unclenick; January 7, 2013 at 06:25 PM.