Bob can answer this better than I, ut info I have shows the side cocker #'s going up into the 9100's Hammer guns as well as the side cockers had thumb push openers. The Side pivot top lever generally i believe began to replace the push opener in the upper 9xxx's. With a # of 90xx this might seem a bit low for a self cocker but the thumb push would definitely not be out of place for that time frame. Perhaps the side lever cocker & the "Automatic Hammerless" guns overlapped in production or perhaps this one was built a bit pout of sequence or was a conversion to a self cocker. Several possibilities. If the price is good would be a nice one to have.
