Below is verbiage of Axel E's where he comments on what constituted reproof in the 8x60mm realm & note the last sentence:

"A mere rechambering job would be marked with the additional crown/R repair proofmarks, with the original proof information still visible."


"The shape of the foreend with the rudimentary Schnabel and the sling swivel screwed through the foreend into a barrel band show the rifle started life as a full stocked commercial Mauser carbine, called Modell S after WW1. the serial number and the BU only proofmarks on the receiver ring date it to 1912. Much later it was converted to half stock and rebarreled to 8x60. It was proofed again March 1930 by the Oberndorf proofhouse. Suhl and Z-M would have marked BUGN allthe time, but Oberndorf marked BU only up to 1923, then BUG to 1934, BUGN last up to the new 1940 proofmarks. The Krupp steel and other barrel markings are unusual for a commercial Mauser barrel, but the RW = Werksrevision = factory check stamps are found on most 1930s commercial Mausers too. Most likely the rebarreling was done by a gunsmith in south-west Germany, who then submitted the rifle for proof to the nearby proofhouse at the Mauser, Oberndorf factory. Rechambering from 8x57 to 8x60 would have required reproof as the service loads changed. Merely the very slight rechambering to the normalized 8.15x46R and 9.3x72R were exempt from reproof as the service charges allowed were unchanged. A mere rechambering job would be marked with the additional crown/R repair proofmarks, with the original proof information still visible."

From a GGCA thread here:

http://www.germanguns.com/upload/showthread.php?1882-Commercial-mauser-8x60-MMs/page2

Cheers,

Raimey
rse