Afternoon all, I'm after some spring advise if anyone can help ?. My son has a Gamo delta fox, .177. I'm just about ready to let him bring his rifle with me when i go shooting so that he can join in on the hunt. the trouble is that it only putting out just under 10 ft/lb of power and I'm not overly sure that's enough power for a clean kill. I don't really want to change the the gun because it fits him really well and he is very comfortable with it. so, with out going on about it, is there a spring that will fit this rifle ?, please bare in mind that it's junior rifle. I don't want to go overbo