Clean 'em and then shoot 'em. Clean 'em more often when they don't yet have many rounds through 'em.
"The sun shouldn't set on a dirty gun." An old saying, attributed to black-powder days, but a good idea, speaking from one who, in his early adulthood, didn't clean his varmint rifle bore much during the season, lest the first shot from a clean bore miss the quarry. The last time I went hunting one season and put the rifle in the closet, next to a sewer stack, I forgot about cleaning the .22-250. A few months later, I picked it up to look at the bore and couldn't see much light through it, due to corrosion. My heart sank and I worked hard to dissolve the rust and get the bore clean, but it was damaged badly.
I was afraid it wouldn't shoot worth a darn, so quickly made up some handloads and drove to the rifle range, 20 miles away. Once there, I posted a target at 200 yards and because none of the portable benches were downrange at the 100 yard mark, I went back to 200 and shot 5 rounds prone, without a rest or sling.
When I walked to the target wondering whether any shots made it that far and hit paper, I was absolutely amazed to see a 5/8" 5-shot group!!! I'd never shot groups prone before and was pleasantly surprised, but my surprise changed to wondering what the heck I put in those handloads!!! Finally, I determined that they were of my regular handload recipe, using CCI 55 grain bullets.
Sorry about the long post. JP