Another failure to chamber thread.... help please

[fanofflyn]

I have this problem too, and that makes sense. I'll give that a go. Also, look at the inside of the upper receiver at the place where the bolt carrier stops when you have the fail to feed. The front of the bolt carrier will make a gouge and a ridge where it is driven into the aluminum of the upper receiver. You will need to smooth this out and polish it. I did that alone, and it helped, but then the problem recurred and the upper receiver damage started again. The long ejector makes sense and that is where I will go next. It also explains why my first sign of higher pressure is an ejector mark before any primer flattening when making my loads. Thanks Rootshot.

--fanofflyn