In Missouri our "muzzle loader" deer season was changed to "alternative weapon" a few years ago and any centerfire handgun is legal. I got my wife an AR 6.5 Grendel with a 12.5" barrel. They have updated the regulations describing a legal weapon for that season that now includes an overall length limit and the gun is 1/2" too long. I am considering cutting the barrel and getting a brownell facing/chamfer tool and doing it myself. I have never done this before so I just have to ask if I have a reasonable chance of success or if I am about to waste $150?