Make sure the barrel is heavy enough and long enough for the balance of the rifle to be forward of the mag well, (at least 3 inches.) so you can balance the rifle on your game changer bag on the obstacle.
If the rifle is too rear heavy you will need to use your body to steer instead of letting the rifle rest while you lightly touch off the trigger.
Heavy butt stocks can work against you unless the barrel is heavy enough to act as a counter weight... so consider the butt stock weight as well.