Sorry Igloo for such late reply. Possible misunderstanding!
Some late war Cz "econo-bolts manufactured without guide rib! All receivers yet underside-bridge slotted for ribs.
Beyond a bit confusing! EARLIEST POSTWAR BRNO SPORTERS... Typically, with rib and detent slot underside of bridge required to "accommodate". LATER FORTIES all Brno sporters and some apparent rearsenaled Brno military 98s, without the bolt guide rib. The sporters were of solid left sidewall design. Such and of tight tolerances, the guide rib superfluous! On the yet traditional thumb cut military, a problem with 'guideless' bolts hanging-up cycling closed.
If all this is insufficiently confusing... Earlier sporters yet retaining the bridge underside guide rib slots, thus guide rib equipped bolts, optional. Later forties sporters, without such slot. Standard mauser guide rib bolt, will not fit! Latter Brno sporters design of the fifties+, returning to full, traditional guide rib configuration!
Last comment These Brno sporters, of half-stock and full-stock configurations; all 'quality'!
Now, don't worry! No "timed test" on this subject required... Today!
Best & Stay Safe!
John