The .177 pellet rifle has potential. A few years back, a buddy got interested in them and competition air rifle shooting. He then got into specialty gas mixtures and modified his Crossman air rifle to take mixtures from a small portable tank. He even got a patent for his modifications. Crossman licensed his patent from him and he’s now fixed for cash for several years to come. His modified Crossman air rifle has the ability to fire a .177 pellet at nearly 4500 fps. This air rifle sounds like a a .223 and will put a pellet completely through a 4”x4” piece of framing lumber. As I recall the gas mixture is half hydrogen and half helium.
I believe Crossman has these for sale now. This would have the ability to seriously get an intruder’s attention. You’ll have to check the Crossman catalogs for competition air rifles.
Baloney.