The 34 is a freakin nightmare to machine, the only way to get the bolt raceway in the thing is either to have it broached in, or find someone with an EDM with enough throat to cut it for you.
The M-60 never impressed me at all, it ran fine when fired in bursts, but if you tried to hammer it, it nearly always went tits up.
The MG-74 that we fired at the same time would take all that you could give it and sit there smokin, waitin for the next belt.
The 34 that we had performed flawlesly in all aspects, besides beatin the livin daylights out of a fella. Another fela who owns a 34 has all sorts of trouble with it, and it all is related to feeding. It will puke every time with Turk 8MM, and is even unreliable with German 8MM.
All the above weapons were dealer samples that we have had at one time or another.
The current HK-21 that we have is unfired by us at present, but another 21 owned by a fella in Southern Ohio is a real gem. You cant jam that thing with a screwdriver and a hammer.
If I had to pick one, I would pick the Steyr MG-74. It looks cooler than a 21 to me!!!!!
Chuck