I've been hanging onto a magazine for one of those things for 40 years.

I have too, was given to me by one of my Dad's friends when we lived onpost in the 1960s. What an interesting little beast-- (These are the spotting rifles for the 106mm Recoilless Rifle--) Numrich/Gunpartscorp had some parts for a while, and you could find some of the others in the Shotgun News now and then-- another boat missed for this kid--but I still have the damn mag! I wonder who would make reloading dies for .50 M8--

Brass has to be getting rare too.

Just as I was processing out of the army, the guy I was leaving the Small Arms Repair Shop to informed me had an M8c (stripped) sitting in the arms vault with no paperwork.
He suggested it could go home with me - I've done some stupid things during my time in but that wasn't going to be one of them.
Still, it would have been cool to have.

I do have a friend who has one but it's mounted on his 105mm recoiless.

UltraLite50 50spotter review

M48 brass from 50BMG blanks

The guy who designed the Safety Harbor, Anzio, etc .50 BMG rifles was the inventor of a side-fed semi-auto .50 S/T rifle back in the late 2000s.  Shot it once, and it was ridiculously sweet...light, relatively little recoil, and badass.  Only one prototype made to my knowledge.  I'm assuming he got his brass as surplus at the time (same era as Talon's demise).

This thread seems to have about as much detail on that rifle as anywhere else on the internet:

https://www.ar15.com/forums/armory/Mag_Fed_Bolts/3-345764/

I had the poster advertising the rifle lying around somewhere, dunno if it's gone or not, but the ad listed it as the USA-50 and an "intrudoctory price $3,950".  OAL 46", 21" barrel, 1 in 15" twist, gas operated rotating bolt, magazine feed 4 rounds, optional 6 rounds, weight 14 to 15 lbs, in .50 BMG or S/T.  Ligamec Corporation 22119 US Hwy 19 Clearwater 33765, 727-480-1711, [email protected] www.Ultralite50.com

I have a magazine and some rounds. I'd like to find a mag in better shape. Or find some of the inner parts and have the rust removed from the outer part.