I was looking at some FC .308 once fired brass and noticed a slight ridge of brass around the opening that pointed inside. It doesn't look normal. This is once fired factory ammo that probably came out of my 40X. I say probably cause doesn't look like it came out of my .308 M1. I'm thinking the neck was too long and the case mouth made contact and peened in brass around the circumference. I made a chamber length gauge and will check the 40x and M1 tomorrow. I tried to take a picture but it didn't show up well. What signs do you get when the front hits the ledge at the end of the chamber?