so i've got a superior arms ar 15, this is my seconed rifle, never had a problem before with them. but now, the rifle wont cycle, i can get one shot and the bolt will only blow back a quarter of an inch, ive been using wolf ammo for quite awhile, i've checked, and rechecked the internals, they look fine, i can't figure otu why it wont cycle..any ideas????
should i have replaced the gas tube?

