A bit of rust / pitting is nothing to really worry about , if you have a half decent round count or just a hard life in general, i just put it down to being used , barrels are just a consumable item .
I would be more concerned about throat being burned than pitting , a barrel will shoot with a pitted barrel I know .
I think some people worry needlessly. The rifle will tell you when you need a new barrel , not the bloke trying to sell you a new one 😂
I have an 30 yrs old .220 swift over 3k round count at 3850/4000 FPS the barrel looks like the inside of a scaffold tube and I will still shoot 0.2 mils .
But glad you have it sorted .