Thanks, Wobbly.
Yes, factory ammo, Atlanta Arms 115 JHP and UMC 115 FMJ. The last photo was after literally a couple of passes with a bore brush and some Kroil, followed by maybe 10 dry patches. To be honest, I don't know what a fouled 9mm barrel really looks like.
The "before" photos were maybe 100 rounds after shooting the little pistol so well at 100 yards that I really didn't want to touch it. I remember using an (inexpensive) borescope on my P-09 barrel after shooting a few 6" groups at 100 yards and it had a lot of particulates and debris but no lead fouling that I could see. I didn't touch it for another 2k rounds or so. Never saw any degradation.
The .22 pistol has to be kept clean, at least at the chamber and leede area. If the leede starts getting some carbon buildup, the accuracy drops off enough to be noticeable. For example, if the zero appears to have drifted off, yet my grip is good, I don't adjust the sight, I clean the barrel, on the Kadet. That seems to fix the issue, 90% of the time.
I have moved from the desert to a much more humid climate. I may have to clean and oil the centerfire pistols more often now just to prevent corrosion from combustion products, not sure yet. So far, I don't appear to have any problems. I leave the guns bagged when coming inside from a cold outdoor range and let them warm up before exposing them to a humid environment where water would condense on them, just like I do for my camera gear.
Joe