I have an extra lower laying aroung and want to do a 9mm, I have been waitng for 9mm bolts to come down in price, but I don't think it's happening. so I might as well jut pony up the 175$ and get it over with. the question: is there any difference between a standard pper and the 9mm upper besides adding the shel deflector and dust cover? can this be done to any upper? does it even HAVE to be done at all? or are there other differences? I see a high price for dedicated 9mm uppers
obviously, only talking about the sole receiver, not barreled
obviously, only talking about the sole receiver, not barreled