"Mint in box!"
Don't be the guy that fully restores his dream muscle-car and then keeps it under glass in a climate controlled garage. SHOOT IT! Remember, an UZI is only happy when it is sending lead downrange. Yours has suffered long enough!
I thought the only UZI pistol was the Micro. The other "pistols" being stockless full-size or minis.
I have a full-size "pistol" that I would love to SBR someday. If that is a possibility in the future.
The advantage to a derringer is size/concealability. Is it my primary or preferred ccw? No. But I do have two rounds of .45 Long Colt in a pistol smaller than my hand that fits easily and comfortably in a pocket. Yes.
:thinking Let me get this straight... you bought a mixed bag of random mags that you don't have pistols for?
Try taking them to a gun show. Some vendors sell mags only. Short of that try your local gun shops/ pawn shops.
Military-based designs, such as the Uzi, are designed to chamber and fire FMJ. Basically two reasons for this.... cost and that damned Geneva Convention. Some firearms will chamber and fire HP, some won't without modification.
Pros- You will get an affordable, accurate, reliable, fun to shoot firearm.
Cons- You will need to get a second one because your wife may be reluctant to share.
If I had a Glock machine pistol, I would get the first one. Cool factor reduction in exchange for more accurate fire when converted.
To convert a semi auto pistol to a carbine? Nah.
I'm no gunsmith, but it sounds like a recoil spring problem. Not seating the bolt forward. Also responsible for your increased recoil on the first round. Good luck!