Who makes a 2 port muzzlebrake for a 50 caliber rifle? This is not a 50BMG. It is a 500ACCREL. It is the 416 Rigby necked up to .510 shooting 750gr A-Max at around 2200FPS. It doesn`t need a BMG brake, just something bigger than a 50 Beowolf brake.
Get the Serbu brake. It is the current standard shark brake that is not to big and is VERY effective. The style is used on almost all typical .50's. http://www.serbu.com/top/contactSerbu.html