Just to clarify, the note about the nomenclature is actually a pretty big deal because a lot of vendors screw this up too. These things have enough differences that when you call everything 308 or large frame an AR-10….then find out you have a completely different barrel nut, a different length gas tube, a slightly wider pin for “xx” a different length buffer tube, the wrong spring, the wrong buffer…you get where I’m going probably. That’s why the right names matter with these, and that’s why some photos and dimensions help the folks on this side of the screen to diagnose the issue and help work towards a solution. These guys can be really helpful, but if you make it like pulling teeth to get the info they need to help you, it evaporates in a hurry. Nobody is trying to be a dick (some of us just are). Everyone here wants the end result to be you having a big smile on your face and a pile of brass next to you thrown by a functioning gun. Help us help you…no problem is unsolvable.