new old stock 1903a3 rebarreling question

[Calif-Steve]

A Scrapco barrel? Oh, my. Mint, and unused, it was made by Remington with a short-chamber. The witness marks line up and you have to ream out your short chamber. Made that way. No thread work is done. Something is not right here. It should not eat a no-go gauge. Not mint, for sure. Let me add this:
Order a new, mint bolt body from Springfield Sporters. They have both S-C and Remington bolts. See if that cures your chamber issues. Good luck.