Yes, 50 Beowulf is a heavy AR round used primarily for big game hunting and some heavy tactical situations, much like 458 SOCOM. It's really only accurate out to 300 yards, and I use the term "accurate" lightly, as it's as accurate as a big heavy assault rifle round can be. But damn is it fun to shoot, mostly just for the "what the **** does that guy have?" reactions you get at the range.
There are guys that have made custom 50 Beowulf bolt action rifles. But I wouldn't put the money into that. I'd just go with a 416 Ruger or something in that vein.