Re: Military Gunsmiths
I'm guessing you checked the carrier key for tightness, and checked the bolt moves freely inside too, and checked that the hammer is properly returning and staying locked all the way back.
1. Try an entirely different ammo. That kinda sounds like 5.56mm in a .223
2. Swap in another recoil spring. Check for obstructions in the tube. Check the bolt and upper for wear, bends, or snags.
3. Consider a new gas tube.
Check the mag release for good tension and adjust just in case it is letting the mag play. Check that the bolt catch has no signs of premature catching.
Never say die!
"A nation who forgets its defenders is soon forgotten itself."
"A good shot must necessarily be a good man since the essence of good marksmanship is self-control and self-control is the essential quality of a good man." – Theodore Roosevelt