Quote Originally Posted by MojoCrow View Post
Some barrels are better than others and some are more sensitive than others.

Some .22 rimfire match rifles have a cycle of cleanliness/dirtiness where the rifle performs at it's best after a certain number rounds have been put through the barrel. The accuracy can start to deteriorate and then it becomes neccessary to clean the barrel and start dirtying it up again until the accuracy returns.

Some barrels are more sensitive to dirt than others (i understand that .17 HMR, .17 Mach2 & .17 Remington are quite sensitive to barrel fouling and the accuracy can deteriorate after 25-35 shots). I have read about new barrels being 'conditioned' when new by routine of firing and cleaning. This is designed to remove and roughness in the rifling.

I've had one customer who was being driven nuts by an RWS Excalibre which was stupidly accurate when operating room clean but wouldn't group for toffee once it had the slightest spec of fouling. I suggested he should try lapping the barrel but i heard months later that he sold the rifle.
Good info! Thanks.