When working up a load, the manuals tel you to look at primers. For low to medium pressure rounds, flattened or punctured primers is way too high. My Uberti SAA will have its screws loosen when I’m at about 75% of max pressure. My Sig P320 will fail to extract a .357Sig case when the pressure is ~10% above max. When I stick my .40 barrel in the P320 and shoot max book loads, the brass will bulge to the point where it pushing it through the bulge buster die requires significantly more force than usual.
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What do your guns do when pressures are near max?