Were the bolts on military 98 mausers individually fitted, or were they made in mass sererately and then given an individual serial number when placed with an action? I can see how the later would be true. Especially in war time. Just wondering.

They were mass produced and are for the most part interchangable. The only problem with swapping bolts around though is often there's a few thousands difference between them and switching them around between assembled rifles can make proper headspacing dicey. As such I would assume that barrel installation was completed after the bolt was supplied.

Then, once everything was assembled, all necessary parts were duly stamped with the proper serial number.

This is what I suspected was the case. Given this, I see no need for a person to pay a premium for an action with matching #'s if he/she is going to build a custom gun. Any other informed comments would be appreciated.

you are 100% correct. If you are going to yank the barrel any way you will need to set headspace for the new assembly.

Matching serial numbers are far more important to collectors than they are to shooters. Hell, most old military rifles have been arsenal reconditioned at least once during their military life, and parts would get swapped out on a routine basis.

A friend of mine who served in Eurpoe during WWII said they frequently removed the bolts from captured Mausers and they would just toss them all in a box that would get shipped back to the rear with the rifles. I doubt many of those ended up with the same bolt they started out with.