I'm not great about cleaning my guns after use, but I've always heard .22lr is dirty. Some say accuracy can suffer from buildup, though I think each bullet probably cleans the bore just as much as it dirties it. I'm not planning on using them for a while, but did shoot about 100 rounds through each. It sure got the bolts dirty, and bits of primer and powder in the bores.
I find the difference in rifling between the two rifles interesting. The one on the rightseems just a little more accurate, shorter barrel, and it could have a slower twist rate, but I didn't check it. It's supposed to be 16, but I measured the other to be about 15 or just under, when its also supposed to be 1 in 16".