Big ass guns you gotta bust with both hands
Most likely a reference to the Smith and Wesson 500, a .50 cal Magnum that is the most powerful handgun in the world. It is said that the gun is so powerful that it can kill an elephant. Obviously, a weapon packing that kind of punch is going to require both hands to fire.
To help improve the meaning of these lyrics, visit "The Message 1 and 2" by Mr. Muthafuckin eXquire Lyrics and leave a comment on the lyrics box