Very obscure and not well know wildcat, but I'm convinced it is one of the most versatile cartridges ever created. Let me explain. Essentially you convert a 12 gauge slug gun into a big bore rifle. You do this by using a very slow rifle powder (to keep pressure low) and brass 12 gauge hulls. There are some stipulations though. The brass shells must be thicker than normal stamped hulls, meaning they are lathe turned. And the shotgun has to be beefy. A bolt action savage and an H&R ultra slug (which is what I'm using) are great choices. The savage can take quite a bit more pressure than the H&R, but they are harder to find and more expensive. The chamber needs lengthened to 3.5" (or 3.85" for the savage). With the slow burning powder you get insane velocities and muzzle energy. One load calls for 240 grains of H50bmg and shoots a 600g solid at over 2500fps. We are talking similar if not more energy than a 700 nitro express. The beauty is, since it's just a lengthened chamber, you can still load up conventional 12 gauge ammunition and hunt squirrels one day to any game on earth the next. This also prevents this build from being classified as a destructive device by the ATF since its still technically a shotgun. I just got the ball rolling on the build so it will take some time to get it completed. The majority of the wait is for the hulls which are made to order by RMC. While I can use slugs, I wanted something more purpose built with better ballistics than a hunk of lead. So I contacted Lehigh Defense about some custom projectiles. I am having two types made. A .729" (bore diameter so no sabots) 600 grain copper bullet and a 1085 grain solid copper bullet designed for max penetration. I think we are going with their extreme penetrator/extreme defense design for the rounds. They should be absolutely devastating on game. So far my costs are $450 for gun $150-$300 for chamber job (estimate) $285 for 20 3.5" hulls ($105 for 10 + reloading kit) The bullets are a very pricey endeavor however and I will post my correspondence with the engineer when I get home. Super excited for this to come full circle. I love big bores more than I can say. A 700 nitro express can run a guy well over $100k. This is a fraction of the cost and is waaay mor versatile. I have honestly never been so excited about a cartridge in all my life.