No 4 Mk 1 markings confusion

[Surpmil]

Is this one of those cases where the bolts got separated from the rifles and the importer was too lazy to sort them out?

I see references to making sure the bolt and body (receiver) lugs mate properly, but not how to do it. One way is to remove the bolt head, spring and firing pin etc. (you'll need to buy or make the tool to unscrew the firing pin), put some blue on the rear faces of the lugs on the bolt body, re-insert into the receiver and while pushing as evenly as you can on the front edge of the bolt body, work the bolt handle up and down a few times and then check the contact shown by the wear to the layout blue. If the contact is not good, some lapping will be required.