I like the .50's.
I have 2 that I have not shot yet--
Barrett M82
and
State Arms KC2000
Both quite nice guns--the Barrett is a semi auto, and the KC is a shell holder type.
If you look in the most recent Shotgun News, there is a special from State Arms on a Shorty (30" bbl) that is going for $1800 (+ about $75 in shipping) with the tac. stock. It comes with a bipod and scope rings for that.
I have seen the Watson's ads, and like the concept. It is slow to load--basically, the "bolt" is just that--it screws into the breech. And, my other worry would be doing something dumb, such as breaking off the aluminum receiver at the pivot by not paying attention when I was loading. But for $1200, it is a good starter for a .50, especially if you already have the receiver. However, if you are going to spend $300 on a complete lower to dedicate to it, the $1800 for the State Arms is probably a better deal.
AFARR