M1 Garands and M14s never jammed.
My Uncle Jimmy from back in da 'Nam said his squad lost at least 10 guys over one tour due to their M16s jamming in firefights. This was in 1965 or '66.
He said it was from that ball-powder crap McNamara insisted on the ammo suppliers using 'cause it was cheaper than extruded propellant.
Never a good day when your mouse gun jams and you have to try fixing it in a rice paddy with Commie x39 rounds flyin' by your head.