I have 400 hundred 180 gr.TCEP cast bullits made by Rushmore bullits. They have I grease grove .they are 0.263 long.what should I use for overall COL.

IIRC, it's 1.260"

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Todd

You either seat them to the cannelure, as determined by observation, or to the COL shown in any loading manual. Generally, and particularly for automatics, the COL is not dependent on the specific bullet. The exception depends on the bullet ogive in that if too blunt or large may require that bullet be seated to less than the Maximum COL. You determine this by "plunk testing" your reloaded ammunition.

Well, the actual powder charged used might just come into play...?

The MAX OAL for 10mm is, as previously stated, 1.260". Almost all Hodgdons load data for 180gr bullets (the exception being the XTP?) is at that suggested length.

How they fit in your magazines, chamber, etc. will be yours to determine. Any clue as to how hard they are?

Cheers!

P.S. I load a similar bullet from MBC (IPD #5, Brinell 18) in both 10mm & 40 S&W with fine results a bit shorter than the MAXs...

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Sit Reloader Sentiret

Not sure where you're getting a BOAL of .263" for a 180gr 10mm bullet? Typo? My 180grs are ~.620".

I like to load my 10AUTOs to the SAAMI max COAL of 1.260", provided they plunk properly & fit/fled from the magazine.

With any proper powder charge weight that COAL" should be fine.

.

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Waiting for the break of day