I had a partial case head separation using a 1.8oz buffer

[LR1955]

First time I've had this happen in 30+ yrs of reloading. I was at the range yesterday doing some prep for the coming mule deer season in WA, when i had a catastrophic failure in round #41 in a box of 50 handloads. I was shooting offhand - first shot of 5 in a mag, and at the shot, the magazine was forcefully ejected, the floorplate was blown out of the mag, and spring, follower, and the other 4 rounds went forward of the line. Lots of "extra" gas. No injury to report other than the initial shock. The load I was using was as follows:

123gr ELD-M
CCI #41
29.4gr AA 2520 (dropped from Redding BR Powder measure - these averaged between 29.35 to 29.6 in the sample set I took - 29.6 is a listed max in the Accurate load book)
Lapua cases (new)
OAL: 2.245"

The gun is an Aero framed pistol built around an OdinWorks 12" barrel with a Midwest Industries rail. The bolt looks fine, but I will be checking headspace and internals with a borescope. The magazine was bowed out a bit on the sides where the floorplate was - I was able to bend it back together, and it test fired great later in my 18" Faxon/Aero. Magwell looks fine so far, but will investigate more when I clean it up.

The plan is to drop this load back a grain or so to 28.5 (Saw this was a fave of DianeB). Rats - 160 some rounds I'll need to pull Either that or save them for a bolt gun I need to eventually buy.

I would guess this round had the old powder measure slip open and add a bit of pow-pow gradually - some of the other rounds near this one had a slight line developing around the case head. I will post pics later if I can get a good close-up.

StH:

You are describing an out of battery firing to the letter. Have had it happen to me twice with the Grendel. Not once with any other cartridge.

If you didn't bump that one piece of brass enough, maybe that is the cause. Or have a bullet seated a bit too long. Could be it short cycled just a tiny amount.

The problem with out of battery firings is no one can ever find out exactly why.

I doubt it was overcharged although I doubt I would go with over 29 grains of 2520 with the long bullets.

Join the club.

LR-55