Lower FPS

So this Farm I was at has at least 300 hundred birds that roost in this one barn.Tin roof of course.I asked farmer joe if I could go in and shoot them at night his reply I see one hole in my roof your outa here😱So here’s my thought.You add more pressure on the hammer by more pressure from the spring.So what I did was remove my hammer spring from the disco removed a quarter of the spring put a screw in the top of the spring and put her back together .My train of thought is it should be a lot lower on the FPS witch should not allow any pass thrus.I also put a 10x32 screw in we’re the degaser goes thinking if I need more power just tighten up on the out side screw.gonna ru it thru the chorny as soon ass possible.
 
I would have just started with a lighter hammer spring and a lower starting fill pressure say 1500psi then fine tune it by adjusting the hammer spring tension as I run it through the chrony and as John said use only wadcutters and 5-6fpe would be just fine. I would have a secondary side arm in a belt holster such as a S&W 6" 586 or 686 with a red dot sight for close quarters work because it is surprising how accurate they are for 10-15 yards effective enough with head shots and five pre loaded 10 round magazines ready to go.

Took out many pest birds and rats in a warehouse all head shots and no damage to the roof and used domed CPHPs in the 586 at around 3fpe at the muzzle with the 6" barrel.


CA