Who did work on your SBR?Same shape here. It's also developing a "L" shape bend on the end closest to the barrel nut. By the way, the 12.5" is still not running with the m4-2000 attached. I think I wanted the ACR to be what I expected, instead of allowing it time to mature as a platform. . . oh well.
Well, I haven't had any troubles with my rifle in that respect but I've worked with the folks at Wolff before on replicating an action spring on a friend's old .22 rifle. They were plenty helpful.That's a great place to look, would you mind sharing how you resolved this issue in case more users develop simliar issues?