12.7 Schuler Short reamer. If you don't run it into the barrel quite all the way, you can get proper chamber depth for a .50 Beowulf.
Lee .50 caliber Minie ball mould. That's .500 diameter like a .50 Beowulf or .50 S&W, not .512 like almost all other .50s. Hollow base, meplat nose, three grease grooves. The Beowulf isn't a high velocity cartridge, so I expect plain old lead should do just fine.
Factory Beowulf cartridge in an ex-USAF M-16 mag. There is apparently a fair amount of variation in the fronts of various mags; they're all just fine with pointy .223s, but the blunt Beowulf snags at the front. A quick kiss with the die grinder ought to take care of things. Also, the inside edges of the feed lips are fairly sharp, and put big scratches in the side of the cartridge. I'll have to zip a Cratex tip over them to knock the burrs off. Again, it probably didn't matter with a .223.
I haven't started on the magwell yet. I plan to just bend it around a steel mandrel, weld up the seam, and weld it to the bottom of the AK receiver. I haven't found any clear pictures of the AR mag release setup yet, though.