These three groups were shot yesterday during ideal conditions at 30 yards benched...using my Huntsman Regal .20 cal, I realized within a group or two that the barrel needed cleaning...two wet (MP5) one dry, quick 5 minute pull through job, and see the difference, my standard for accuracy at that range. If this Regal was a .177 or .22 I would polish the bore but being a .20 I will just clean as needed every couple hundred shots or so. My Bobcat is the same way every couple hundred pellets or so it will tap me on the shoulder and say "clean me" and that barrel has been polished...my .177 Huntsman doesn't care...it always shoots great...oldest and nonregulated best shooter, polished it years ago...my Veteran doesn't seem to care either clean or dirty also polished years ago, but all do their very best after cleaning...I can always tell after a few shots...I can only envy barrels that yield guilt edge accuracy (to my standard) with out ever being cleaned...not talking dime size groups at 25 or 30 but the pellet on pellet overlap...easy to tell the difference...(pictured example)...Clean barrels have always worked best for me.