Lake City 5.56mm Primer Crimping

Since this bug has everyone shut in, I thought I’d catch up on some reloading. Going through a batch of LC headstamped 5.56mm NATO marked casings, I came across casings with curious crimping. Most of the casings from '07 to '16 have the full circular primer crimp, but some with headstamps LC12, LC13, LC14 and LC15 had four stab crimps. Is there a special purpose for the stab crimps as opposed to the circular crimps, or is it just a manufacturing anomaly? Thanks, Bruce.

The stab crimps are a result of increased pressure loadings for the “new” M855A1 EPR loads. The US Army significantly increased the chamber pressure for this round, and the deeper stab crimps are required to secure the primer - especially when fired from M249s with worn chambers. As a reloader, I HATE these stab crimps, they are much harder to effectively remove and ensure smooth primer seating.

Thanks, Joe. That explains that. Having had a Dillon 650 for years makes things easier for processing and, despite what the Army may have concluded, de-capping the stab crimped casings was easier than the circular crimped casings. Also, I have the Dillon Super Swage 600 and it knocks the stabs smoothly back. Thanks again.