This is Belom 7.62×39 123-grain brass FMJ ammo.
Some of the finest brass cased 7.62x39mm you’ve ever seen. Made in Serbia, the Belom 7.62x39mm 123 Grain is a Full Metal Jacket round. These are packed in an ingenious polymer tower with the Belom crest molded on the top, 20 rounds to the box.