Well I made it to the range and back today. I'm still whole, all arms and legs still attached. I still have the use of both hands. I only had the 10 pcs of brass to work with, so only loaded up and fired 10 rounds. I was surprised how fast we went through those! I did let my buddy shoot a couple, so he could try it too. He had to shoot it wearing a glove (he's delicate), and refused to try it "bare handed". I had no trouble shooting it bare handed. It never felt like it was going to come out of my hand.
Now first off, this is a 16" bbl, and it's brake'd, but the recoil was surprisingly mild. It was there, don't get me wrong, but no where near as bad as I was expecting. There was no muzzle climb at all, the gun only recoiled straight back. The report was not as great as I thought it would be. It was a sharp "crack", like a rifle round, but not a big "boom" or anything. It was quite reasonable with good ear muffs on. My buddy brought his 10" 357 Max barrel, loaded with max charge of 296 and 110 gr XTP's, and it was pretty close on volume, but his was a much deeper "boom", so it seemed louder to a few bystanders we asked. We DID cause one "tacti-cool" shooter to pack up and leave in a huff because we were making so much noise though. I consider that a "victory" for the 'tenders!
The recoil was definitely there, but not even close to the recoil of some of the smokeless 45-70 rounds I've fired from my 14" brake'd 'tender bbl. The 45-70 would buck up sharply and try to twist out of your hand. Not so the 375 JDJ. I also think my smokeless 45-70 rounds were louder. The blackpowder 45-70 rounds are still far and away the loudest, deepest "BOOM" so far out of any 'tender bbl I've fired.
I was shooting it just off of my rear tall ear bag, with the butt on a piece of carpet. After the first couple of rounds, I started just shooting it one handed, since it was only coming straight back. Next week I'll be shooting it from my front rest and rear flat bag, with the wide fore end on it, and actually try to hit something with it.
I did pick up some more brass and bullets today at Cabela's. So next Sunday I'll have 100 rds, and can actually run up a few series of test loads to see what it likes.