I never once had a mechanical malfunction in my M60's, and some of those were O-L-D old. We're talking Vietnam old. Unless you include the GOD AWFUL BFA (blank firing adapter) - firing blanks with an M60 was an exercise in futility.
I couldn't shoot the M-16 (A1 or A2) to save my life. Never qualified higher than Marksman with that POS. Expert in .45, 9mm, M60, M203, but that damn M16 was an enigma for me. Never got a chance to shoot an M-14, but did some familiarization fire with a G3, and shot the heck out of that thing
. Though the FN-FAL gave me fits, not sure why.