I've RIA drawings specifing barrel markings on a new USGI rifle Which marking is not really authorized. Personally, I wouldn't use a drill push. It may be completed, but I'd personally go the router or mini mill route. Many thanks a great deal of for chiming in with the details https://coltm16a1forsale34344.blogocial.com/5-essential-elements-for-colt-m16a1-for-sale-67217047