I bought one last year from AIM surplus in early summer.
Got a good price and the only hard problem I had was finding magazines. Numrich had some after market
ones but both did not work, in fact the steel side bulged after loading making the magazine hard to remove- returned them with no problems.
Found some real used magazines at a little under a hundred a pop, but they work fine.
Bought the 1951 for a 80's retro match in October and everyone who ran the "hotel chainsaw" leg of the match loved it, zero problems.
Unfortunately took it out at Xmas time and the barrel locking block cracked, so now the gun is an over sized paper weight.
Debating either trying find a block. Which is not easy or cheap, or parting out the gun, selling the magazines and using the gun for a "buy back program" for a gift card.
Basically I'm not sinking any more money on this gun.
I hope you have fun with yours.
Regards,
Dave