Start here. The rail on the PAP M77 is the same the N PAP M70>>

Yugo M77, NPAP, OPAP Optics (consolidated thread) - The AK Files Forums

 

I just got the Midwest Industries side mount and really like it for mine. Its rock solid, easy to put on and take off. They say it pretty well is on zero if you remove it, I will know this weekend as I will take it off and on several times to see.--- On another short topic, my gun is new and was slapping me in the cheek. If yours is also, look at the post I just put on yesterday on cutting my stock to fit.

 

Took it out today, took the MI side mount off and put it back on 3 times. Each time it was dead on. I am impressed.

 

The MI clone mount works as well.

Tactical AK Railed Scope Mount for Hunting | eBay

 

RS 103 or RS3, as they call it, is suppose to be great.