I guess you know these guns better than I. Which one needs those things? I shot the M-60 in the Corps probably five times. SWEET!! What’s the safety wire do?
On the M60, the gas cylinder plug could unscrew under sustained firing and take off into the weeds, disabling the weapon. We used the safety wire to keep the plug from coming loose. I always carried a spare plug and wire. I fired the MG42 only once and only for a few rounds but I don't think it had that problem.