You mean the weapon condition drops a crapload when it is fired? This is because the dmg done and condition depleted are proportional to eachother. The more dmg done with each shot, the more its condition is lowered. If you look at the original snipers health, it is 100. To fix the issue simply raise the health of the weapon the same scale as the dmg. So if you doubled the damage, double the weapons health. If you made it do 10x as much dmg, give it 1000 health, you see? This should eliminate the problem. And have the weapon deplete its 'health' at the same rate as the normal sniper. If you want it to last much longer than the sniper, than give it twice the scale of health or something. (i.e. for 2x dmg, give it 4x health, etc) Hope this helps.
Gunmaster95