I edited you image to indicate a locking flange/plate thingy. Try flattening it out and loosening the nut it holds in place. This should help with the side/bottom screw.

I don't think you need to get the sprung bolt out at all. Think that once the back bolt is undone you can slide the rest through whilst pressing the spring bolt (could be wrong)

wondering if it's something weird like reverse screw thread or push in to unscrew?

As i recall the head screwdriver depth is pretty thin, maybe you could take a dremel with a cutting disc to make the hole deeper for the screwdriver and get more purchase

one last thing does the rubber plate where the screw goes come off without the screw? wondering if there is something behind it that is locking the screw?

well this is the guy. doesn't look very special in terms of any locking mechanism. I suspect it's just a bit seized up and quite tight in terms of tolerance. With my gun i think i ended up cutting the stock part off around the screw after which it was easier to remove it. Not the best option i guess but it did the trick for me.

brpguns.com sells mg42 parts. Reach out to them and see what they have. They sell most all the parts to build a full on semi auto mg42.

Looking at my stock [a Yugo M53], I can depress the sprung bolt, and there's maybe 5mm of travel. It's been years since I've had the stock attached to the receiver; my Yugo just lives in a dark corner of my safe.

Guessing, but I think you'd need find a way to loosen that nut at the back (you can just see mine, looks a little rusty), with a pair of needle-nose pliers, working around the sprung bolt ... ?

Had another play, The [external] "head" of that vertical bolt is slotted, but looks to require a specialised tool, which I don't have. I was able to turn it with a chisel [my g/dad was, no doubt, spinning in his grave at that ), but it doesn't seem to really do much for releasing the bolt itself.

Better plan I think, is to try and flatten the metal 'collar' that holds the nut captive, and then you'll hopefully be able to spin the nut up [compressing the spring] to give the bolt enough travel to move down out of its 'socket' on the [inside] top of the stock. The metal on mine seemed soft enough to bend with pliers when I experimented, but I didn't try too much, as my stock is part of a working/complete firearm, and for now, I don't want to do anything that I can't undo later.

These folded flappy bits


Also, just to close it out as 'thing to try', I was unable to move the large internal nut holding the horizontal bolt in. Dunno if it's maybe corroded or welded in place, but doesn't seem look it's meant to move (at least not while the vertical bolt is in the way, ... things might be different if I could get a socket wrench onto that bad boy!)

Had another play, The [external] "head" of that vertical bolt is slotted, but looks to require a specialised tool, which I don't have. I was able to turn it with a chisel [my g/dad was, no doubt, spinning in his grave at that ), but it doesn't seem to really do much for releasing the bolt itself.

Better plan I think, is to try and flatten the metal 'collar' that holds the nut captive, and then you'll hopefully be able to spin the nut up [compressing the spring] to give the bolt enough travel to move down out of its 'socket' on the [inside] top of the stock. The metal on mine seemed soft enough to bend with pliers when I experimented, but I didn't try too much, as my stock is part of a working/complete firearm, and for now, I don't want to do anything that I can't undo later.

These folded flappy bits


Also, just to close it out as 'thing to try', I was unable to move the large internal nut holding the horizontal bolt in. Dunno if it's maybe corroded or welded in place, but doesn't seem look it's meant to move (at least not while the vertical bolt is in the way, ... things might be different if I could get a socket wrench onto that bad boy!)