Maybe it’s your trigger or trigger guard stoping it? I suppose you have to get a larger guard and a smaller trigger to get a troll size finger in there.
i just found out (the hard way) that just because it says full auto when you buy a bolt carrier group doesnet make your gun shoot full auto.
stupid bullshit.
Don't know what the difference is between bolt carrier groups? Let's take a look!
www.80percentarms.com
I assume that an 20" H-BAR, rather than a pencil 14"(pinned/welded)-16" would have more rise due to lower barrel weights, and less thermal mass for heat-sinking/cooling.