the thicker part of the carrier also squares as it goes through the sight block. If piston is not completely in, it's out of battery and it won't fire. Safe.
That's a pretty shitty fit, carrier is wobly and you can see how badly the carrier smacks the piss out of the rear trunnion. That AK is shit. Bulgarians have pref treatment on AKs in US, selling capitalists the poison that they crave.