There's also a difference between the .22 Long Rifle "sporting" and "match" chambers.
The match chamber throats are considerably shorter, essentially designed so the "full diameter" portion of the bullet engraves itself into the throat, where there can be a little "freebore" in the sporting chamber with typical.22 LR ammunition.
Somewhere around here I have a gauge that measures this difference, and over the years found that many (ir not most) very accurate "sporting" .22 rifles have shorter throats....
