This may be helpful for some due to parts are hard to come by.
I purchased a used SP-10 that had been abused.
to straighten the tube I knocked in 19mm long sockets, you can remove the magazine cap with a thin
walled deep socket. Gently heat the tube, using a wooden dowel and pass the 19mm to straighten it.
The thread pitch of the SP-10 is 1x28 SAE.
Use a couple of strokes and lots of oil and slowly turn it onto the receiver and back off. Rise wash repeat.
I then took 600grit and worked up to 2000 with a wooden dowel from Lowe's to polish the inside of the magazine tube. Also used a dremel with a abrasive polishing pad and gently and a low speed polished the magazine follower.
Put it all back together and the rounds come flying out of that thing.
Not pretty but the end result is this old war horse is back in action
LOCTITE USING 690 and never touch it again!