Hello collectors! Original unissued WWI Springfield 1903 inspection bolt stop spring. There are several available! Most people can’t figure what that tiny hole is in the left receiver rail on their milled pattern 1903 rifle. It’s for the inspection bolt stop spring & plunger assembly! This prevents the bolt from sliding forward when the rifle is tipped downward to check that the chamber is clear! That is also why there are divots underneath the one locking lug on an original milled pattern WWI bolt! These are original USGI WWI SPRINGFIELD PARTS! Get ‘em while you can!