i mark my mags for all the different calibers i have. I also bought green rubber band things that have 300 bo, 300 hmr, 6,5 grendel ect that go around the gun by the barrel nut. That said ive shot 1000s of rounds and probably loads with 20 different bullets and have tried them all in the chamber of a 556 and the only ones ive had that would chamber were loaded with the 110 and 120 tssx tipped barnes x bullets. They taper off to the point real fast and have a very long pointed nose and will chamber. They only thing i use those bullets for is hunting because there to expensive to just blast at the range.