300AAC case length

[6622729]

To get started in 300AAC last year I had purchased a bunch of already converted military brass and in general they came trimmed well short of the maximum specification so case growth is a non issue so far. In general, with supersonic 300AAC loads, does the brass grow? I don't have a good handle on it yet because though I've shot a fair amount, I have a lot of brass so none of it has been cycled much yet.

[DocSavage]

The brass will "grow". My experience is when you resize the case it will stretch .003-.005 " in length.

[joelpend]

It is almost a straight walled case so I would not expect firing to make the case grow much.

[allsy]

I just started reloading 300 Blackout last week, my converted LC brass mostly 14 headstamps has grown .002-.003 with an original trim length of 1.358. The LC bras has been loaded twice both times it was sized, it grew. I have not annealed the converted LC brass. My PNW Arms factory brass is short after its first resize at 1.354. My Remington UMC (Barnes Brass) is also short at 1.354-1.356.

[6bg6ga]

I set my length to minimum. I have fired cases 4 times and have not had to re-size them.

[osteodoc08]

I trimmed to minimum on factory Gemtech brass and LC converted and haven't had to trim in the last 3 firings.