IMHO & based on a limited number of samples - The Krag barrel-threads, location of extractor cut, rear sight holes, front sight base mounting, and 'Index Mark' were all very precisely 'Timed'.

I believe all the manufacturing work, proofing, and 'browning' was completed on a Krag barrel, before, it was screwed onto a Krag receiver, (stopping, when the index mark that was located on the front edge of the receiver, matched the index mark on the barrel).

This would be very Labor Intensive and not how a manufacturer would likely do it nowadays, but, a high degree of interchangeability was achieved.

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