I would like to have a 22BRX that is a walking weight varmint rifle. Are there any factory rifles I could buy that you can take the barrel off and rechamber to 22BRX? Anything you buy would probably be a longer cartridge. I assume you would have to cut about 1/2" off the back of the barrel and rethread it because the cartridge is short. Looks like it would have to be a 223 or 22-250 to get the correct bolt head diameter and a 14 twist or faster barrel. I think I need a 10 twist if I want to shoot any bullets above 52 grains.