As I understand it, Krag barrels were tested with special proof cartridges (developing 70,000 lbs. per square inch) after the bore was drilled and an interim chamber reamed.

This happened prior to the barrels being rifled. The un-rifled barrels must have been screwed on to some type of 'master action' for proof firing. (They likely were stamped with a "P" at this point).

After rifling, the barrels underwent all of the finishing operations: multiple straightening's, final reaming, 'timing of threads, drilling & threading sight-holes, brazing front sight block in dovetail, and 'browning' (bluing).

Krag actions went through their intricate manufacturing process and were proofed sometime after heat-treat. I suspect, the actions were screwed onto some type of special 'master barrels' for testing.

I don't think a Krag action met its ultimate barrel until final assembly. Close tolerances and gauging must have allowed the index marks to 'line up' as the finished barrel was screwed into the finished receiver.

'Timed Threads' & parts finished before assembly - It blows my mind!  (Not how it would likely be done today).

Once Krag rifles or carbines were assembled, I believe a percentage were subjected to firing another proof cartridge, all were tested for function, and received the "Circled P" on the stock wrist.

I could have this process wrong in part or whole. I base my understanding on the "Scientific America" description of Springfield Armory manufacture of the Krag.

I've also attached a later description of the final proof of 1903 Springfield rifles. By that time, all assembled rifles were proof fired before receiving "P" stamp on stock.

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