This Ruger manufactured straight slot blue finished takedown screw is for the model 10/22 semi-auto rimfire rifle in 22LR caliber and is in very good condition with light wear. (file photo)
Note: Ruger model 10/22 semi-auto rifles with the following serial numbers have been observed with this part:
10/22R: 198421
10/22RB: 128-72693
K10/22RB: 250-58382