Originally Posted by Cole125
Its a answer to a non existing problem. Mil spec uppers are more than durable enough. On top of that the MUR does not work with many upper receiver vise blocks.
A rifle can never have enough durability. The vice block thing is no big deal IMO. I just used my upper receiver action bock and cut a piece of my derlin kitchen cutting board to support the flat top rail, and off into the bench vice. Works like a charm with absolutely no flexing. The best receiver vice block I have ever used on an upper.