Hey bro; Catfish is right, no need to reinvent the wheel, it's all been done, some with better results than others, the good lord only gave you two eyes and ten fingers and one life, personally I would not risk any of them, I don't think anyone is trying to insult you, just trying to prevent you from becoming a statistic!!!
I understand there are men out there you just can't reach!!! If you are one of these guy's then by all means be careful and work your way up on the loads you are creating, as the results could be catastrophic, I would only use a single shot break action, reason being you don't want additional rounds being subject to accidental discharge should one of your creations run amuck!!! I would suggest a heavy Bull barrel like a NEF Pardner in 3" Mag, they are very inexpensive and should you blow it to pieces you will not be out a lot of money. make sure you do not fire these loads your self, you need to find a tree out in the middle of nowhere and secure your gun to it and use some para cord and tie it to the trigger and get as far away as you can and preferably behind something structurally sound!!! I don't know how much reloading experience you have, if not much, then you need to read up on everything you can get your hands on, there are so many variations to reloading it will make your head spin, should you use a bullet that is heavy and a powder that burns fast it all over, and that's just one, ammo company's spend literally millions on research creating the perfect round and market it to all of us, with all the home work already done, most guy's that reload do it to save a little loot or if anything down load a round to a more controllable round, if you are going to try and build a shotgun round that exceeds 3,000 FPS or something crazy like that, stop and think about it, if that were doable they would be selling it to us, believe that!!!, fact of the matter it's just not safe!!!