I did my own as well. Turned out it wasn't as difficult as anticipated. I bought 416 Rem Mag bottom metal from Swift and then started by making the bottom of receiver match up to it. I used a Dremel tool with grinding wheel for most of that work. I also picked up a magnum follower from New England Custom Gun (though the standard follower works okay I'm told). Opened up the end of the receiver till the longer follower came up freely. Then I started working on angling the feeding ramp, removing a little metal and trying a dud shell until I had it right and tip of bullet moved up without bumping into the receiver. Surprised that the left feeding rail required no modification. Very little was needed to reshape the shoulder area of right rail to get top two STACKED loads to cycle. The problem was third shell was hanging up under the right rail. Rather than alter the rail and risk taking too much I decided to change the follower. If I took too much metal from the receiver, I could always fall back on the standard length one or order another magnum follower. Take too much metal from rail and receiver is no good. End of project. So I carved away some of the upright feeding ridge in the follower. Started about quarter inch ahead of the back end of follower and took out enough metal to allow the shell to jump sideways at the point where it was binding on receiver rail. Left the quarter inch untouched at back to ensure the last cartridge didn't roll out prematurely when loading. It works perfectly! Last issue I finally resolved last night was snap over wasn't consistent loading shells dropped in the magazine. Kinda important to fix that as this dangerous game rifle only holds three in the box. I relieved some spring tension on the extractor and that did the trick. Removed the extractor and reshaped it by bending the bow slightly. That did it. Also seems to make the action cycle smoother for some reason. Probably allowing shells to pop up into bolt face easier. It is now very slick! I never did a thing to the 416 bottom metal. Worked fine as is. I actually anticipated opening it up a bit to satisfy Paul Mauser's cosine 30 degree formula for stacking in the box but it wasn't necessary.