Beautiful rifle,,casecolor and condition just outstanding.

The early 39 bolt uses the same bolt as the Model 97 did before it.
Early production Mod 39 used up some of the other parts from the discontinued Mod 97 also.
The 97's can only take Standard Vel too or you'll end up w/a busted bolt.

On the later 39 bolt, the sharp angle where the locking abutment meets the bolt body was given a small, gentle radius to avoid the cracking problem from stress of the HV ammo fired in them. Probably beefed up the locking abutment too over time as they did lots of other small changes inside.
Great rifles.

I have a couple 97's and shoot them w/ stand/vel .
Original bolts would be a tough find I'd imagine if you needed to replace one now..the early style pull tube magazines are tough enough and expensive to find replacements as it is.