Terry Buffum:

"The marking ' A O Niedner, Dowagiac, Mich' means the rifle predates the Niedner Rifle Co. I'm sure one of Michael's books gives the date of incorporation of that company, but it is around 1920 as I recall."

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Petrov says this stamp was used 1920-1929. Which consideration seems to establish that this rifle must be chambered for the pre-Remington (1934) wildcat original .257 Roberts.

Any more opinions on altering the chambering to either the commercial .257 Roberts (Remington) or to the .257 Ackeley Improved?