I have an HK factory MR556 barreled upper that I would like to have a gunsmith cut and re thread. Obviously its a piston upper. I understand that due to the shorter barrel, the gas system may have to be opened up a bit, so its more that just a cut and thread. I would like the flexibility to run the gun with a can or without also. Ideally the gunsmith would have done this with an HK upper before.
Thanks in Advance.
Thanks in Advance.