45
Anything is possible, but why would you want to? And from the standpoint of somebody who is practical, why would you want a rifle chambered for the .50 BMG? Sure it feels big and bad, and dont get me wrong it is, but there are options out there that, with a bit of finesse, can out perform it. And hell, if you really want something big, check out some of its bigger, European cousins. Steyr has their 15.2mm monster, the Russians have the infamous 14.5 and then there's that Croatian monster, the RT-20 which fires an old cannon shell.