It was not a manufacturing unit concern for that model. Potentially Inventive crafting of a regular inventory. Pictures would assist to find out the appx calendar year your rifle was built. 44 It was supplied from about 1959-1963. A further defining attribute of the JTSS is it came using a https://highimpactrounds.com/product/winchester-ammunition-long-beard-xr-20-gauge-3in-6-1-1-4-oz-shot-lok-lead-1000fps-10-rd-box/