J E CUSTOM,
I have and I know many others that have used the 50 BMG or wildcats based on it for big game hunting. In every case concerning the other hunters, they purchased the 50 BMG thinking it would be the ultimate in big game long range weapons, used it for a season or two and then realized it had the same trajectory as a 300 Win Mag and dicided it was not worth packing around 25 lbs of rifle in the field.
In a quality rifle, the 50 BMG is a very consistant and accurate weapon, it has to be fed a diet of quality ammo however and that can take a great deal of testing. Most 50 BMG brass is made to mil spec so its great for strength but seldom great for precision. There is some out there that works pretty good out of the box but as a rule, you should short your brass by volume.
Every hunter I know that has used the 50 BMG at long range has used H-50BMG powder and CCI-35 primers with the 750 gr A-Max bullet loaded to the 2500-2650 fps range.
On lighter game such as pronghorn and smaller deer, you will get a 1/2" hole in and a 1/2" hole out. On heavy game, say an elk, if you landed a 750 gr A-Max on the onside shoulder, you would likely loose the entire offside shoulder. Its not really desired to have that big A-max open up, remember we are packing nearly 12,000 ft/lbs of energy at the muzzle and in most cases over 6000 ft/lbs at 1000 yards. A 1/2" hole through the vitals does pretty well to anchor game.
I do have guys come in the shop all the time asking me about my wildcats and after talking about them many of them will make a comment about the BMG and how it would be great to be able to hunt with something like that. My comment is that a 338 Lapua with a 300 gr SMK loaded to 2850 fps will SMOKE a BMG as far as bullet drop and is not far off with windage. If your really hung up on performance, the 338 wildcats on the 408 CT case simply make the 50 BMG look silly as far as drop and drift numbers. Only area that the BMG has the edge in is kenetic energy but there are many standard calibers that have more then enough energy for hunting at any thinkable range.
Certainly not trying to tell you not to hunt with the BMG, just realize what it is and what it does. It throws a HUGE chuck of lead at moderate(for todays standards) velocity. It is not a laser gun, in fact it drops like a rock at long range but it does hit hard. They are heavy, long, just big in every way, loud and funner then hell to shoot. As long as you know what your going to get out of a BMG you will be happuy, if you expect the ultimate in long range performance, if your hunting trucks, then yes, but for thinner skinned game, you like most will eventually fall back to the more conventional rifles.
My accuracy load in several 50 BMG rifles I have owned was 215 gr H-50BMG under a 750 gr SMK with the CCI -35 primer. OAL varied with the specific rifles. Velocity was in the 2600-2650 fps range and groups in the sub moa range at 1000 yards was not all that difficult but you had to have consistant ammo to do this.
Just what I have been around.