I lived in a state that allowed rifles for fall turkey hunting. Ideal turkey rifles were thought to be the .22 Hornet, .218 Bee, the .25-20. When the 5mm Rimfire Mag made its appearance in the 70's, some guys bought it for a turkey rifle. The .22 mag was used as well, but the centerfires were more popular and better killers to hear fella's talk.
The aiming point was always the butt of the wing. The head is an elusive target. Heck, spring gobbler hunters miss turkeys heads, with shotguns, at under 30 yds, more often than some will admit. The idea is to run the bullet above and behind the breast, catch the lungs and spine.
The .22 lr was not considered a turkey rifle, but doubtless squirrel hunters potted a few. I have killed one spring gobbler that had a .22 cal bullet wound through the breast bone. Completely healed over and healthy ( super spooky) trophy tom. Migrant tree planters likely shot him on our lease a few years before (they were caught later).
If its true that a .22 mag in a handgun is the ballistic equal of a .22 lr from a rifle, ie the .22 mag looses a bunch of steam from the handgun, then I cannot endorse it as a turkey round from a revolver.
If you are good enough, and disciplined ehough to only head shoot turkeys with a revolver, and its legal, carry on. Hunting turkeys, fall or spring with an iron sighted handgun should be a heck of a challenge. I myself would not be eating much turkey.
I tried bow hunting spring turkey...once.... and got humbled really quickly.