Hello Jordank,
I dont own, and have never shot a 50 BMG however Ive done quite a bit of research on them. As far as purchasing goes, there are a few VERY good manufacturers out there. If money is not a concern, id recommend either Barrett, Accuracy International, or Robar. Accuracy International makes a rifle callled the AW50, its very expensive, but Ive read that its a real tack-driver on the range. The same holds true for Barrett's M82A1 rifle. Barrett actually makes a few different models of their "light fifty" each with a different price tag LOL
these are the M82A1-a semi-auto, the Model 95 which is a bolt-action created for more accuracy (its also the medium as far as pricetags go), and finally the model 99, which is also a bolt action .50-only it is a single shot version, as opposed to the other two barretts which use magazines(clips).
As far as Robar goes, im not very well informed on their product but im sure they are worth checkin out.
Oh and if you dont want to spend your lifes savings (lol) try checking out Armalite,or LAR mfg.,
GOOD LUCK TO YOU I HOPE THIS OINFO WILL BE USEFUL TO YOU, oh and if you need anything else please email me
matthewb@zoominternet.net glad to help out!!!