Dave,
Rings on the #1 are the same height back and front. How could you tell that they were reversed?
Douglas and others made some of the early barrels too. But there is no real way to tell who made a given barrel. The date of shipment is all that Ruger can certify. The component parts went into bins for the assembly line w/o any particular concern for assembling parts according to date of manufacture.
Recent production, black pad, rifles are most likely to have in-house made barrels that meet modern chamber standards in all calibers. The earlier overlong chamber problem, judging by cases cited my owners here and other collector sites, was most
prevalent in 7x57s and even then was not uniformly or even commonly the case.
Odds are that, as Bricktop said, your 30-06 should be fine. If not, check for bedding issues as well as the chamber. The right hand load also can fix erratic groups.
Good luck,
1B
