Group size:
Throughout WWII the standard specification for acceptance of the Kar98K was a 5 shot group of 120 mm or less @ 100 meters. This correlates to a maximum 5 shot group of 4.32 inches @ 100 yards. This was with SS ammunition, not the more common SME load. By all measures the latter cartridge was not as accurate, with 5 shot groups on the order of 5 to 5.5 inches at 100 meters with some lots not being unheard of. Such accuracy is not all that impressive if one considers the M1903A3 was required to put 5 shots in a 3 inch group @ 100 yards with average grade 30-06 M2 ball rifle cartridges.
However the documentation that exists from the factories indicates the average rifle could produce much better accuracy. Rifles selected for optical conversion, either as marksman's rifles (ZF-41, 1.75 x) or sniper rifles (all other 4x to 6x power scopes) was 5 shots in a group under 60 mm @ 100 meters (no shot not contained within the scoring template), corresponding to a maximum 5 shot group of 2.05" center to center @ 100 yards.
Most interesting in examination of these documents is that the factory test was not sufficient to select the very best rifles, as a 5 shot group at 100 meters was not sufficiently discriminating, the Army weapons office preferring 10 shot groups @ 300 meters. The documentation indicates that a reasonable percentage of rifles could pass the 60 mm requirement and that given the number of shots there was no real way of assuring that the most accurate rifles were in fact being built up as sniper/marksman's rifles. The preponderance of evidence (including modern firing tests) indicates that the "average" Kar98K would produce groups well under 3 MOA with good ammunition, and that a good percentage of rifles off of the production line were capable of well under 2 MOA. While by no means National Match quality, such accuracy is sufficient to clean the SR 200 yard target, which is used in vintage rifle competition.