Com Bloc, TAPCO, I.O. Inc Waffle pattern, ProMag, Bulgarian AK 30rd Mags...
East German, Bulgarian Polymer AK-74 Mags...
Mag compatibility was done with milled Bulgarian reciever, krebs custom built on a Russian Siaga, Century built Yugoslav underfold, I.O. Inc hellcat and a RPK built kit on a US made reciever..
Com bloc, Bulgarian and ProMag fit all of them..ProMag was tight on milled gun and Krebs Custom..
I.O. Inc mag did not fit milled reciever..
Tapco only lock into the I.O. Inc hellcat and the RPK..
East German and Bulgarian had zero issues on a number of ak-74 pattern rifles..
He ran the shooting portion through I.O inc Hellcat, Krebs custom ak-104 7.62x39, old Romanian MKII in 5.45x39...
Heat tested to 160 degrees for 4 hours, zero issues encountered during shooting phase..
Cold tested to 0 degrees chilled for 48hrs, zero issues encountered during shooting..
Rear impact test, simulate if rifle was dropped...Rubber mallet using moderate force 10 times..
Com bloc, east german and Bulgarian absorbed all 10 hits without issue..Also absorbed a further 10 fairly heavy blows without issue..
Tapco failed after 3 blows, mag catch broke..ProMag after 9 blows mag catch broke..
Bulgarian 7.62x39 mag broke after 10 moderate blows and an additional 3 heavy blows..The I.O. Inc mag after 6 blows, but enough of the mag catch was left to lock into the gun and fire all 30rds...