. I don't think you can build a 50 in anything much lighter than 25#s with most being in the 35-50# range. Anything any lighter would severely run the risk of physically hurting the shooter. This thing makes a 460 Wby look like a 38Special. Run the numbers, stoke a 750grn 50 caliber bullet up too 2900fps and you can imagine the kind of recoil it generates. I believe the ft#s generated by the bullet is somewhere in the 11k too 15k ft pnd range
The 50 BMG that I built weighs 29 pounds. There are several in the 18-19 pound class and one thatweighs 12 pounds.The recoil is suprisingly easy due to the very efficient muzzle breaks.In fact,shooting my .300 Mag Sendero hurts me worse than shooting my .50.
There is a guy that I work with that has a doe being shot on digital camera. Its a 10 second clip. The shot was at a doe walking across a power line right of way. The range (laser range finder) was a measured 732 yards. It dropped the doe on the spot with a hit to the shoulder using a 750 grain A-Max.