I think that is what it's called, the flat spring external on the bolt stop lever. In any case, picked up a Remington with original 5/18 barrel, typical rebuild, parked, all looks right but for the chromed spring. Stock is nice shape, bore a has some pitting but still pretty good, nice lands and grooves. Thinking maybe a VFW rifle but why just one chrome part? Any way to remove chrome chemically? Thanks