If I could get any 5.56 beltfed, it would be a SAW, but that's a dream, so a Shrike and an MM23E had to do.
I haven't shot the Shrike for a while, the last time out, my brother had 2 or 3 belts go fine, then I tried and it wouldn't run right. I don't know why, probably tight links. I have since added the plastic bock to prevent the wear issue in the feed ramp.
My MM23E had issues so I had to send it back twice: last time I ran it I had 3 belts through and it ran great. I really have to go out more with it.
It's a bit heavy, so the MM hasn't been shot in a while either. The MM has no issues at all with tight links: there's so much energy in that bolt the empties are flung 20 yards, and the case mouth gets really deformed. Forget reloading half of them... and the rate of fire is impressive: a $40 belt is gone in less than 8 seconds...
Since my M60 hasn't had any issues, anything I've shot since has not lived up to the hype. But then it's hard to keep fed...