I did the work, such as it was ;-) The hardest thing was taking apart the Mark I. Everything else just slid together. It is an Ares kit, about half the price of a Browning, and maybe, given the rail, a little more versatile. The serial is on the pistol receiver and rifle receiver, not on the "lower", so it is legal to switch back and forth. With a half dozen magazines it is very easy to burn a box of 525. No FTF/FTE with Remington or Federal. No luck with sub-sonic except one at a time. I'd welcome a solution for that. The grips were made 45 years ago from an apple crate slat.