Re: Casing Dents on 5.56 M855
Look inside the dent area itself. If you can see a sharp corner or sharp crease in the bottom of the dent, lay them out. Otherwise enjoy. As long as the metal in the cartridge case isn't weakened by a sharp crease, you should be good to go.
If you have any doubts in your mind look for the worst one of the lot. Then examine it really close. Put it in the rifle, put on your safety glasses and ear protection and pull the trigger. If the one with the largest dent makes it OK, the others should be fine.
Usually the dents are just where they have come out of the machine and hit each other. 99.9% of the time they are fine. Especially US manufacture.