SOrry can quite figure out how to embed a picture
I didn't have a piston driven AR variant , and didn't want to spend H&K money So after getting one to many Atlantic Firearms Flyers , I bought the Wolf T91 12.5 upper and built a pistol.
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Observations . The upper is heavy , and a for a 12.5 a bit undergassed. On the first range trip I was getting 2 or 3 soft strokes per magazine using Winchester White Box. After that range trip , I made 2 changes. First I swapped buffer springs , I switched to the Wolf Reduced power buffer spring,and I lightly honed the chamber. Now it seems to eat everything quite reliably. ( I am not sure I am keeping this optic set up on it as it adds weight to an already heavy gun) I am learning to love this mut of a gun though.