I found this paragraph in the Frank de haas book "bolt action rifles". Due the the different rim types and diameter of the rounds it sounds pretty risky. I would not want to be near when he conducted these tests.

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Proofing with an overpressure charge is a routine thing. Getting good proof loads is somewhat hard today. I imagine that it was back then also. Proofing usually is done at a safe distance or containing device and the trigger is remotely pulled.
Screwing a 30-06 barrel on for one firing would be easy and have predictable pressure. I wish I had thought of that. The one thing it does not do is give you is the results of a new barrel on the Krag. If you install a new barrel and it is out of spec your test with the 03 Springfield barrel is incomplete.
One proof load is thought to make an action stronger by moving the metal till it is properly loaded on all the mating surfaces. Cracks could develop if only one small point of contact is made on the locking lugs over time.

King carp wrote on Apr 8^th, 2019 at 9:59pm:

. . . Due the the different rim types and diameter of the rounds it sounds pretty risky. . .

The US Krag action, appropriately barreled and chambered, is perfectly capable of handling rimless cartridges with the rim and body diameter of the 30/06. Neither of these features presents any particular hazard in itself - it's the higher pressure of standard 30/06 loads that exceeds the design limits of the Krag action. (Some US Krags in ceremonial service were re-chambered for 30/06 blanks and used extensively with such low-pressure ammunition.)

The very similar Norwegian Krag action is designed for a rimless cartridge (6.5x55) with slightly greater diameter than the 30/06 and handles it nicely.