A punched triangle next to the "3" in the outside ring of numbers would mean that at the last armourer's inspection of the rifle, the bore measured 6.53. The other mark identified on the site linked (0-3) refers to overall bore condition (pitting and the like). After a "3," it got rebarreled. Between the two markings, you know the condition very well as of that last inspection, assuming, of course, that the disk went with that rifle.
There are at least two monographs in English on the "Swedish Mauser." They disagree - largely on historical details. I know a gent with over 200 of them. He says both of the authors/author teams are "full of it" - again on historical details. Everyone agrees these are fine, well-made weapons that fire a cartdrige both reasonable in felt recoil and easliy suitable for game up to deer. (My uncle the WW II pilot shot bear with one in Alaska, but it's not recommended. But neither is getting shot down three times.)
The versions made under contract by Mauser Werk were also excellent rifles.
Strangely, they often close on a "NO GO" gauge when by every other way to evaluate condition (including examining fired cartridges), they are in excellent condition, making me wonder if we have our gauges wrong over here.
The stock sounds like (hard to tell for me from the pictures) Artic Birch - has nice, bold patterning. I have heard some old stocks were used to make handles on Scandi-style knifes.
