MKIII (MILITARY)/MODEL 1910 (SPORTER) RIFLE Description
replaced the previously used solid lugs which traveled vertically, has the "triple thread, interrupted-screw, double-bearing cam bolt" with the bolt head traveling horizontally.
It must be noted here that ALL rifles Military and Commercial that Ross built on the basic 1910 receiver have either M-10 or M-1910 roll-engraved on the receiver ring. This being the case ONLY the .280 Commercial Sporter is correctly referred to as an M-10. All other variants have their own designation, and are clearly not M-10's. This has increasingly been used, usually deliberately to the seller's advantage, on Internet Auctions over the last few years, and amounts to deliberate misrepresentation. The newly-designed bolt replaced the previously used solid lugs which traveled vertically, and has the "triple thread, interrupted-screw, double-bearing cam bolt-head" with the bolt head traveling with its lugs horizontal, rather than vertically, as with the two previous designs.
It is these models where the report of "bolt blowbacks" have occurred. The bolt on these models, could, with some difficulty be rotated 180 degrees and hence not close completely. If fired in this situation, the bolt could blow back and potentially injure the shooter. Sporters were produced in three grades: R (economy), E (military box magazine and checkered wood) and the top of the line - the M-10.