This Stevens manufactured third variation trigger spring screw with the larger flat head is for the Favorite single shot falling block rimfire rifle and is in very good condition exhibiting a grayish brown patina with slot wear. (file photo)

Note: this part is commonly found on the Stevens Favorite single shot rimfire rifles with 8th thru 10th variation receivers. The following serial numbers have been found on 8th variation receivers with this part: Q402 and Z757.