Quarterbore's Forums - 300Whisper trim to length 1.355 not 1.400!

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- - 300Whisper trim to length 1.355 not 1.400! (http://www.quarterbore.net/forums/showthread.php?t=453)

300 AAC BLACKOUT is 1.348 to 1.368.

Trim to 1.360.

is the blackout the same case?

everybody agree that i should trim to 1.360"?

pinched necks and blown primers

I say 1.355 is a good length and I will be trimming to that measurement from now on.
I wish I had found this thread before making brass. I had two pieces of brass at 1.395 and 28 more pieces at 1.375 inch. The 1.375 brass shot ok, but the 1.395 blew the primers. (Savage bolt gun, and could not tell any difference upon firing. The primers fell out of the pockets upon ejection) Looking at the brass you can see how it pinched the bullet at the neck and made the pressures spike. I measured the blown cases from the base to where I can see it begin to taper. On my gun it looks like the chamber is somewhere around 1.360 -1.365 long.

I am making all my brass 1.355 inches long from now on.

1.358 is center of the 300 BLK range.