So i put a call in to a firearms tech at the rcmp firearms program. Not only was he un-awares that you could use 10 round 7.62x39 pistol mags in a rifle legally, he was also uncertain if you could take off some metal from the same mag to make it fit an remain legal. I have an e-mail in to that department as of Wednesday. Hopefully they will get back to me by new years for inquiring minds. There isnt anything in the act that Ii can find that specifically forbids it. Im still gonna mill my receiver, but some of you might want to try this mod with only chopping magazines. Hope to have an official response for you guys soon.