Call of duty black ops zombie question.?

On Call of Duty Black Ops, is it worth upgrading the "Dragunov" into the "D115 Disassembler"? If I'm correct an upgraded sniper does 1000 damage, the same as a ray gun. However I'm sure these rounds will penetrate multiple targets and you don't have to worry about shooting yourself. I was thinking of using it as a secondary gun/backup gun to mow a horde down or kill the thief/dogs/monkeys.