Hi DeerhoundLurcherman...!
Sorry if I'm wrong but, I get the impression you are not a highly experienced air rifle shot.
There's no reason to tune up the power to FAC levels or switch to .177. You just need to understand your pellet's trajectory loop from the power at your rifle's muzzle a bit better. And how it relates to your scope's reticle in the sightpicture. IE, where your shot is actually going under shorter, and over longer ranges than your basic zero.
For example, if you zero at 25 yards and you want to be able to hit a target 15-20 yards further on, you need to raise the