TargetTalk

You'll often read or hear someone claim that their barrel needs to be shot-in after a thorough cleaning to restore its accuracy. I think that I've observed this affect w/ my match AR, but haven't noticed it w/ my pistols.

IF a barrel is more accurate past a given 'dirty' threshold, what's likely be be occuring?

I believe it has to do with lead, copper, and powder fouling filling in the microscopic grooves/pits inherent in any barrel. That said, I'm no expert on such things.

In .22rf., and other lead bullet firearms, I believe it has to do with re coating the barrel with bullet lube. When testing different brands of .22 ammo, I was taught that you have to remove any trace of the previous bullet lube to get accurate comparisons. After this cleaning, it was necessary to fire several "fouling shots" before firing for group.
Paul

Yes, for .22lr, a slightly fouled barrel is often more accurate than a squeaky clean one, due to being lubed up. However, a fouled does not equate to filthy! If you let it go too far, the accuracy will start to fall off and the barrel will become inconsistent. Clean may now be the mot accurate, but it is at least a known quantity, and accuracy won't start to fall randomly with little or no warning.

Given that it is impossible to recreate a given level of "foulness", it's often best to start with a clean barrel (since clean is clean - or is at least a known quantity), and just ensure you have a good half dozen "blow-off shots" on your sighters to make sure it's ready for the shoot.

Back when I was shooting SB prone, I couldn't afford to shoot fouling rounds in the backstop. {10 cents each} I watched where the rounds went at 50 yards with my 20X rifle scope and I could put them all in the same bullet hole after each cleaning without foulers. I was a much better shooter at 50 than 100 so it usually took more sighters at 100 and my barrel was well fouled by then. Even so, I remember firing several rounds in the middle of the X ring and quickly going for record before the wind started to blow at 100 yds. That also could have been the second stage when the barrel was already fouled.

I suggest testing if you are concerned, however, there are many more factors affecting the bullet than fouling and it is difficult to see with an air or .22 pistol.

BTW, my barrel was oiled after every cleaning which was after every 40 shot match. Maybe the oil in the barrel had something to do with it.
Ben