I'm using a .22 lr conversion kit with my AR-15. Lately I've had problems with failures to feed. It's like the bolt won't push the round all the way into the chamber -- it sticks out a couple tenths of an inch. I keep everything super clean. I have put thousands of rounds through it. Are any of you familiar with these? Have you had a similar problem? I thought the recoil spring may just be wearing out, but thought I should check with those of you who are most likely more experienced in these kinds of things. Thanks!