Ok, so IF I get enough money to do this reasonably soon, here is how it's gonna go down.
Cartridge-20 gauge 3.5"
Brass-Rocky Mountain Cartridge custom turned 3.5" brass
Barrel-20 gauge USH
Action-SB2 rifle action
Stock-Custom set from Riflestocks Inc. that will have room for lots of recoil reducers
Dies-Custom set from C4HD
Bullets-1040 grain cast
Pressure limit-30k PSI (This almost exact project has been done before, I talked to the guy who did it, the brass is the weak link at that pressure)
First, I will locate a 20 gauge USH barrel and send it to get reamed to 3.5", and have a long rifle-like throat added to reduce pressure and allow bullets to be seated out. This shouldn't be more than $100 with shipping. Then I will get 20 brass made, for about $150 shipped. Dies will be around $200 to my door as well. A custom stock set should be the same price, $200ish, plus the cost of either several recoil reducers added, or just some lead in the stock. I will see if I can get an especially wide forearm made so I can put lead on either side of it, and weld the forearm stud on so it can't break. I know a smith who can drill and tap the front of the barrel for sights, and also install some, hopefully using the scope mounting holes. I will have to buy a press to handle the big dies, but the Lee should be plenty strong and under $100. With the 30,000 PSI limit I can achieve around 1800 fps with a 1040 grain bullet, but I don't think I could handle that, around 1500 or 1600 fps would be much softer recoil. Speaking of recoil, if I get the weight to 15 lbs, the recoil at 1600 fps will be UNDER 100 ft lbs. That's not a whole lot more than my 45-120. If the weight is 12 lbs, recoil jumps to 118 ft lbs, but with a good recoil pad I don't think that would "hurt" persay. But, at 12 lbs, the 1040 grain bullet at 1800 fps is kicking with almost 150 lbs recoil. I don't think that is practical.
So, there you have it, my entire thought process. I don't see anything unsafe, or that sounds iffy, but if you have concerns feel free to voice them! I talked to Ty Herring of Barnes Bullets about my project, and he tol me his version of a "Poor Man's 600 Nitro" as he calls it. He used a TC Encore frame and barrel, and shot with pressures over 18k and much thinner Magtech brass. He said the H&R action and barrel are both stronger than the TC Encore and will take more pressure. His gun was only 7 lbs, he shot it with a scope, and it had 147 lbs of recoil. So if you know what you are doing, 150 lbs of recoil is obviously conquerable, even with a scope. (Don't think you'll catch me on Youtube breaking an eye socket however
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Here is a picture that is very close to actual size of some cartridges for comparison:
EDIT-Nevermind, it got shrunk. Use your imagination.
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