Tuning Wildcat barn power level question

Greetings,

I have an FX Wildcat Mk III Compact in .25 caliber. It’s been a beast with pest birds and rodents out to 100 yards plus. It came tuned from Utah Airguns, and I’ve never shot it off power level 7, or modified it it any way. My question is, what ft/lb level is safe for shooting indoors in a barn with galvanized roofing? I’ve never shot or zeroed off full power on the Wildcat. I’m sure I could find a good short range zero at a lower power level, but I’m not sure how much is too much in this setting.



My friend has an enclosed feeding area for cattle, that now has a massive problem with roosting pest birds. How many ft/lbs are too much for a galvanized tin roof? Can I turn the power wheel low enough on the Wildcat to help, or do I need to shop for a low power barn gun like the PROD. Please tell me I can achieve this with my gun. I don’t have a wife to contend with, but I am a single dad of a 14 year old girl who says I am wasting her college funds. 
 
Might it help to get a piece of metal the same thickness as the barn's roof and use it as a test target? That would provide some direct feedback on pellet types and power levels. I live on a farm with a couple of old barns and there's generally a piece of metal roof around somewhere. Our local metal roofing supply shop has scrap roofing I'm sure they'd provide for test purposes. One of the worst whippings my Dad gave me was when I was a wee lad happened when I shot a couple of holes in the barn roof with my .22 trying to snuff a pigeon. Yep, rob_g is right about farmers being touchy about their barn roof.