Question. Picking up a used AR upper in .50....I can't seem to find anything except old posts. Is there a company that makes new magazines for this upper? Videos on how to make your own? Anyone still shooting .50 AE upper? All I hear is crickets.....it feels like I am the only person on earth with one. Any help/direction would be appreciated .

Wow thank you. I will look him up. I appreciate the heads up. I have not tried anything. I am still in not possession of the upper yet. I am biting at the bit though

50AE uppers were originally made by American Firearms in Commerce City, Colorado. They came out in 1994 and retailed for $599.
They went out of business around 1996. Hesse made a few 50AE uppers around 1998 - 2000 or so.
I made about 300 uppers from 1999 - 2005 and sold barrels, bolts, magazines, to build your own as well. Dalphon also put together uppers using some Tromix parts, but they went out of business before many were shipped. American Firearms and Hesse both used the Desert Eagle spec rifling twist of 1:15. Accuracy was not very good, so I had a rifling button made for 1:25 twist and had Pac-Nor make the barrel blanks. Those barrels would routinely turn in sub-moa groups.

I still have the forming tooling for the magazine followers as well as followers in-the-flat. I don't have any magazine spacers though. I still have the tooling to make those, but I would need an order of 50 or so, in order to make it worthwhile to fire it all up again.

The weak link, is the bolt and the extractor. The good news is if they are going to fail, they will usually do so within the first 200 rounds or so. If they make it past that......you're probably good for life.

When you get the upper, take some pics of it and send them to me at Rumore@Tromix.com and I can tell you who made it. None of them were marked with the manufacturer except the very last of the Tromix units.

Tony Rumore
Tromix

I got creative with my latest personal 50AE build. 12.5" brl, car gas, custom twist blank, LMT super bolt(the ones they dont make any more) & a little more throat on the chamber. I run the 300g Speer GDHPs at 1900fps with 37g LilGun @ 1.67oal.

I can help you with mag conversions

I'll donate some brass.

I started saving once fired range brass from the range rental desert eagle with plans to build a AR one day. All these years later and no 50ar :( 300gr at 1900 is sweet!
Shoot me a pm when you're ready.

Not Don but I'll answer, thats a ARMS #36 extended rail/riser if I am not mistaken. I actually have been considering one for a non AR project [taking my tri rail that I removed the side rails on and attaching the ARMS rail underneath on the bottom rail so my FS2000 can take a rail mounted flare launcher]

http://swfa.com/ARMS-36-Super-Extended-Optical-Sight-Rail-P6079.aspx

I am totally humbled. You'all are walking, talking, fountains of information!