It is NOT a normal trunion. The Yugoslavs have a special rear trunion and handguards. They do NOT interchange with other AKM's. The PAP is a special animal too. Reports on other forums are that the ACE receiver block for the Yugo pattern AKM's requires a bit if modification to fit due to the rivet pattern.
BTW - The bulged trunion refers to the barrel trunion where the barrel is attached to the receiver. Browsing images of the O-PAP showed both styles.
BTW - The bulged trunion refers to the barrel trunion where the barrel is attached to the receiver. Browsing images of the O-PAP showed both styles.