The 99 didn't survive Y2K. Its older than that, sometime in the 60's probably. Recoil pad is non factory. Pictures would help with an estimate.
You can tell the year by looking at the lug where the lever hinges. On the front of it you'll find a stamped oval with letters and numbers in it. Usually no more than 3 characters. The letter will determine the year. This system began in 1949 beginning with the letter A.
