I have the biped for a halo 2 sniper jackal, but when I go to give it a 2 handed weapon in the .biped file it doesn't show in game view. I've changed the animations to "sg" which is the label for the weapon I want it to hold. But it still doesn't work.

So basically, how do I make a Jackal hold the beam rifle?

The only weapons that the Halo 1 Jackal animations support are the Plasma Pistol, the Plasma Rifle, and the Needler.