My can is about a year old and half gone. I shot again today with two other 58's too, rifles that have liked it in the past. They still like it just fine, while the recent acquisition still hates it.
Now you have me wondering with your description of accuracy deterioration, and I'm going to try something. In the past when I ran into either sudden accuracy problems or a change in fouling it proved to be accumulation in the bore not removed by my normal cleaning. That was especially true back the days of "conditioning" the bore with Bore Butter or Wonder Lube. I've been assuming this rifle was shot very little if at all, but now I wonder.
In any case, the past solution was a really thorough bore cleaning to remove any accumulated residue. The best I've found for the job is a little brake pad cleaner on a succession of patches. It takes the bore back to bright condition and sure solved the problem. I hear the same for carburetor cleaner.
