I got a 300 blackout upper during a recent bout of spending some of the money Unkle Joe sent me. I was just going to make some brass out of some of my 223 brass that I have laying around. I have a bunch cut off and sized but can not find a neck reamer. I seated a 30 cal 147 gr FMJ bullet in one of my cases, no primer or powder charge, and it will jam in the chamber, it is too tight even after using the factory crimp die on it. I did have a reamer once but it has disappeared , Midway is out and also incidentally, out of empty brass that is reasonably priced. So I am just thinking of making a reamer out of a drill bit. I can modify the point but will the spiral flutes cause a problem. What numbered bit comes close to .311 . Does any of this sound at all feasible ? Thank you for any guidance or wisdom you might share.