I saw one of them earlier.
Something was wrong with that ac-556, he could ONLY switch from 3 round burst to full auto with the hammer down.
I think he said he expected that to be the case, not sure why he would expect that.
Likely someone assembled it wrong and it forced it to heather and bent something.
I was able to switch mine from burst to FA anytime I wanted. Hard to control? Now make it a compact. Shorter barrel,lighter, folding stock. Glad I sold mine. I got low end AR conversion price for it too. Making it a silly choice. Just spend a couple grand more and get a Colt sp1 conversion
I watched it yesterday. It is always great to hear his input on any weapon. Forgotten or not. I was not aware of the round counting ratchet action in these guns, and how it functioned in full auto. It is a interesting piece of machinery.