My Miller & Val Greiss hammer drilling bears a date stamp of 6,13 (June 1913) & was the 240th gun proofed that month. The rifle bbl is proofed @ 8.8mm/72 & the chamber id properly dimensioned for the 9.3x72R round. It bears a Crown/N followed by K.M.G./12.7gr (Copper Jacketed Bullet of 12.7 grams [196 grains]). It does not have the word "Nitro" written out on the rifle bbl, but does on each of the shot bbls (16g).
I cannot absolutely verify the following but read it from a source which I considered as reliable at the time;
The 9.3x72R was essentially given 3 types of loads over its span of popularity .
1 - a black powder loading
2 - a smokeless loding basically duplicating the black powder load & suitable for use in BP proofed guns
3 - a smokeless powder loaded to a higher intensity than the former two.
It was further stated that all 9.3x72R guns bearing a "Nitro" proof were proofed for this later loading & that cartridges loaded to this intensity level had a slightly increased rim thickness to prohibit their use in BP proofed guns. The guns bearing the Nitro proof would of course have had a corresponding increased depth to their rim seat to accomadate the thicker rims.
