I've seen upper receivers for M16s in .50 AE several times online, but never actually seen one upclose. Anyone ever fired one of these?

Are you talking about firing the m16 .50 AE or just .50 AE in general?

I've fired a desert eagle .50 AE, kicked like a mother fucker, rounds were more expensive than a .454 casull(which I think is a better round) and desert eagles aren't worth all the hype.

As for the ar-15(I doubt they'd be m16) uppers in .50, never seen one,never fired one. I doubt it would be that usefull since the rounds are so damn expensive and limited in number and brands.

I've never seen .50AE uppers for a AR.

9MM AR uppers are common, come with bolt, bolt carrier, charging handle, magazine well attachment and most of the time a couple mags.

I've seen those go for $200-800.00 depending on manufacter, post or preban.

olympic arms makes a .50 AE upper. I am told the balistics out of a 16" barrel are amazing (I have never looked them up my self). The draw back is that you will be limited to 10 round magazines as there were, to my knowlege, no .50 AE uppers produced before the crime bill of 1994. But hell, you shouldn't have to hit them more than once with a .50 ae.

The .50 AE is an overrated round. You shouldn't have to hit anyone more than once with most calibers. Unfortunately, the one shot stop seen in movies is very rare in real life. People that can actually put a round where it needs to go are also pretty rare.

considering the range of rifle rounds it would seem stupid to put in a conversion system that uses expensive pistol rounds unless you are using and "entry" type short barreled rifle.
as for the 50ae round being overrated-
they do have an extreme kick and they do cost a lot of money, but as for one hit stop power you have your wires crossed when you say(imply)that 50ae doesnt have one hit stopping power. the 50ae is about the strongest pistol round available.
the 50ae round can completely penetrate class III hard body armor that can stop multiple 5.56mm military rounds.
unfortunately the desert eagle is seen almost too much in the movies.

I might be wrong, but as far as I know, the .50 AE isn't made by very many manufacturers. That means no gold dots or hydra shocks. All I've ever seen it in is fmj roundnose. Off the top of my head, the .45 super probably has alot more velocity and energy, plus you can put whatever kind of bullet you want into it since there's a gozillion different types available for .45 acp.

There are soft points and hollow points made for the 50 AE. Yes, while a .45 super is a step down from a .50 Action Express it will do just about everything that a .50 can.

I believe that with the .45 uppers you can use the easy to find thompson stick mags.