IMHO and experience 22 WRM works better thru a 22 LR barrel than it does thru the original 22 Mag barrel. It has been my experience that most 22LR pistol barrels run about 0.2235" bore diameter. I have two M 617s that are more accurate with 22 Mag than they are with 22 LR. I saw a M 17 with a 8" bbl that became an absolute tack driver with a 22 Mag cylinder and cartridges. ......