Gun shops often get it wrong
 

A favorite gun shop sells a lot of used military arms. They had an 1891 Argentine Mauser that had been sporterized by Bubba. I did not want it, but they advertised it online an an 8MM Mauser. I called the store and pointed out their error. They appreciated the clarity. I doubt that an 8MM Mauser cartridge would have been able to be chambered. All the best...
Gil

I too doubt an 8x57 cartridge would fit a 7.65x53 chamber, but, better safe than sorry.
I've run across a number of similar errors over the years. 98's marked as 93's, etc.
The most interesting one was a long time back, when a whole rack of M-1 carbines was at a large gun shop that had a nice range and would let you try before you buy. I perused the rack of carbines and picked one up that looked just a hair different. When I asked if I could try it, they handed me a 30 round magazine, loaded, and sent me to the range, where, I pointed down range, loaded up, and proceeded to dump 30 rounds into the backstop in one burst. The gun was an M-2. :)

I hope you bought the M2
 

During college days I worked at odd jobs. While working at a gas station on the PA Turnpike, a coworker asked me if I wanted to buy an M1 carbine for $50. I checked it out and it had a selector switch. At that point the M2 carbine disappeared. All the best...
Gil

I wish!
Of course, everyone heard the burst of full auto fire, including the gun shop staff, and the M-2 was quickly with drawn from availability.
I still have a Mexican Mauser 98 (small ring) that a gun shop seemed to think wasn't as good as a large ring, and priced accordingly. The barrel looked like a rusty sewer pipe inside, but, I wanted the action for a future custom rifle project.