22 Birdshot in a regular rifle won't be worth a crap over bout 5 feet because of the rifling. It destroys the pattern.
I have an old Remington pump that was used in the late 60's to 70's for Mo Skeet. Those are minature clay targets and were shot with the old crimped 22 birdshot. The rifle has an actual choke in it and looks like a 410 from the muzzle. It REALLY wacks a rat or snake within 15 feet with either the crimped or really sings with the CCI loads.