It's more important to protect the bore from moisture than be squeaky-clean. When we were varmint hunting as young adults, I didn't clean my .22-250 after each outing, just so it would shoot to the same POI. At the end of one season, I left my Rem 700 ADL in the walk-in closet, leaning next to the cast-iron sewer vent stack and forgot about it for a few winter months.
One day, I decided to check it, because I remembered that it may not have been cleaned at the end of the season (being newly married, had other priorities). Well, I could barely see light when looking through the bore!!! My heart stopped!!! My palms got sweaty!
I plugged the bore and filled it with WD 40, then left it for a couple of days. It was difficult to get it so a rod would go through, but I took it easy. The bore ended up being quite pitted.
I decided to check it out at the range and expected to see keyholes on the target, if it hit the target at all, so I hand-loaded a few rounds without being too careful about documenting the load. I got to the range, set up a large target at 200 yards, and noted that all the portable benches we used at that time were downrange, so laid down on the firing line and ripped off 5 rounds without a rest, not being very careful.
When I walked down to the target, I expected to see keyholes or missed shots, but there it was...a 5/8" group!!! Prone at 200 yds??? How the...?
I immediately tried to remember what I had loaded into those rounds a few days before!!! I still don't know.
I kept the rifle for a couple of years and it continued to shoot well, but someone was looking for one at a good price and I sold it...with full disclosure!
JP