The single number is Bulgarian. Russian ak74 has 2 numbers separated by a hyphen. The ak100 usually has a raised circle. Ive pulled some new blocks from current sam5s without the lightening cuts on the piston housing. Some older blocks i have from.bulgy kits have real gnarly cuts. You can definitely tell ak100 by just the shape as well. But the russian ak74 which was commonly used on bulgy guns as well looks nearly identical besides the mold numbers
Right on, Huge thanks for the info, I appreciate the detailed answer! I was planning on listing the block so I wanted to make sure I had the origin correct before I list it with bad info.