This is the Anschutz 6 round .22LR magazine for the Anschutz 1761 rifle.
Made from stainless alloy with a tough polymer base grip it is strippable for cleaning. They are stamped as 5 round on the side of the magazine but in practice take 6 rounds of .22LR.
This is a revised version of the first 1761 .22LR magazine, with improvements to the feed geometry. The new design has a black feed guide insert at the front.