The E-10 is contemporary with the M-10 Sporter. It was a somewhat more economical model and as you can see, it has an exposed magazine vs. the M-10's hidden magazine. The E-10 shares the same action as the M-10 and their military cousin, the Mark III. A frequent source of confusion among the later Ross rifles is the receiver marking - M-10. The M-10 Sporter was marked M-10 as were about seven other models. This E-10 is marked M-10 and the MkIII's were marked M-10. In fact, I recall when I purchased this rifle it was advertised as an M-10. As I explained to the seller that it was not an M-10 he was struggling with taking the opinion of someone he had never met vs. the rifle he was holding in his hands which was clearly marked, M-10!