It's the BC that is the prime factor in windage. You can pick pellets with the same mass, and the same calibre, and have quite marked differences in windage... a .22 pellet with the same BC as a .177 pellet takes about the same wind... so in the end, if ranging is an issue and you have the same BC, then .177 is more accurate. That said, you can get better (and worse) BC's with some .22 pellets, so if windage errors are more of an issue than rangefinding, then that's where it might be worth looking.
Depends what the problem is as to the approach...
BFTA/NSRA County Coach
CSFTA Chairman/BFTA Rep