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Message: <blockquote data-quote="diggler1833" data-source="post: 3912351" data-attributes="member: 48072">Forgot to add another lesson I learned the hard way when it comes to pushing max loads - Not all brass is created equal.  There are pretty significant case volume differences between brands sometimes, which has a significant influence on pressure. It hasn't been that long ago that my neighbor bought a large frame AR from me and I gave him my 168gr SMK/IMR-4064 recipe that was a solid 1/2 minute performer (which is pretty rare in the semi auto world).Anyway, he came over with the rifle, some 165gr Sierra Pro Hunters, and Federal (Lake City equivalent) primed machine gun brass.  Powder was IMR-4064.We started at a pretty respectable (1) grain over starting charge.  At 1.3gr (.3gr increase) I noticed ejector swipes...thought "it has to be the bolt", and kept going.  At 1.6gr over minimum the swipes were extremely pronounced, and like an idiot I kept going because we were almost 3 whole grains under max and you can usually compress IMR-4064.  .3gr more (1.9 over minimum) and I blew a primer on the first shot.I took it back down to just 1gr above starting, and messed with seating depth until he got consecutive groups just under an inch.  I was happy with that accuracy...he thought it should shoot 1/2 MOA <img class="smilie smilie--emoji" loading="lazy" alt="🙄" title="🙄" src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f644.png" />.I have 2K pieces of Lake City 7.62x51 once fired brass myself.  Once I get about halfway into the powder charge range, I start to develop pressure signs as well.  Anyway, just more semi-coherent rambling.</blockquote>

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