I found this Mannlicher-Schoenauer Model 1910 Receiver. It has matching serial numbers on receiver and bolt and is dated 1925. It seems all original and complete. I was told this bolt has a 6.5 bolt face and it does look the same as the bolt head on my Model 1903 6.5x54 MS, but it is marked 9.5 on the ejector, so is the 9.5 x 57 bolt face just the same as the 6.5?

There is also a spare bolt (marked 9.5 on the ejector) that has a cut at the rear for a receiver sight. Bolt face looks the same as the bolt that is numbered to the receiver.

Left to right: the bolt in the reciever, the spare bolt, the bolt from my Model 1903. They all look the same to me. Although I wonder about the "K" stamp on the receiver bolt. My Model 1903 has a "K" stamped on the bottom of the magazine. (The Model 1910 has "9.5" stamped in that same spot.)