Runs With Scissors: As I understand the markings, a 1 means perfect or near perfect bore with little or no chamber/throat erosion; a 2 means there is some, and a 3 means the next step is a rebarrel - by Swedish military standards.
Savage T has a M96 that had a 3 marking and his shoots great. I have a Ljungman with a 3 marking and I think it's a tackdriver. My sporterized M38 gives me snake-eyes at 150 yds.
I think the markings may indicate the number of thousands of wear the barrel/chamber/throat may have suffered over time, so if the barrel starts out at a .264 bore and yours measures .266, although it may shoot fine for your purposes, that might mean it's a '3' marking and after a certain period of time they would have rebarrelled it. I think.
I think I also hope someone has some more specific information about this. We had a good post, and I think it was from either S. Sumner or Savage T, maybe a year or so ago, and it addressed the issue well. You might possibly find it if you cruise on down through all the pages on this Mil-Surp forum. HTH. Mikey.