I think that we might be getting into the weeds here.
The '40 is when the gun was repaired by being rebarreled and then inspected. The marking is a defined SOP.
View marks tend to be when some work was performed. No repair = no inspector sign off, no view mark. If the barrel was not replaced, it would not have that date shown.
Depending on the repair and who did it (factory or unit armourer), there may or not be an inspector mark. Inspection markings tend to be for substantial repairs. With the age of this rifle, it may have had a second barrel change or more. No way to tell.
No number on the bolt tends to make me think that the bolt was changed out by somebody other than an armourer, who would have marked the bolt with the rifle serial number if he was doing his job.
There are new old stock un-numbered bolts floating round on the market. This might be a post service replacement, but no doubt, armourers sometimes missed out renumbering (naughty armourer!). So nobody can say for certain, but I would guess at post service replacement bolt.
Providing that there is even bearing on the locking lugs and headspace is within spec, it is good to go.
These rifles did a lifetime or two of service, and then several more lifetimes in civilian hands. That is a lot of years where the civilian owner could have serviced and repaired it, including replacing a lost bolt.