want to get an air gun that will knock down a coyote 50 to 100 yds.
That's the crazy thing I found out too. I was all excited to hear you could get larger air guns, not so much when I found out how loud they areI looked into air for a while until I found out they were as loud as a .22. Not much help for the neighbor that is anti everything I believe in.
45 Caliber Big Bore Pellet Rifles, High Powered Air Guns for Hunting at the Best Sales Prices notice it says loud as hell.
AirForce Texan Big Bore Air Rifle. Air rifles - PyramydAir.com
either one will do job, but I think your looking for stealth.