What is supposed to screw in here (Diana 34)?

Hello. What is supposed to screw in here (hole far right) and does it matter? 
image.1633137862.jpg

 
Large flat headed screw that goes there. They are almost always missing because when people mount an optic they remove them... I believe it is a stop screw for a scope ring but... ???

Makes perfect sense to me
1f914.svg



It is not a stop screw, if the screw is used as such it will sheer off. That hole is intended for a peep site, the screw is just there to plug it. Yes most are missing because they are removed to scope it and never get put back in or lost. I put mine in a bag and label it in case I want to put it back in later.
 
Large flat headed screw that goes there. They are almost always missing because when people mount an optic they remove them... I believe it is a stop screw for a scope ring but... ???

Makes perfect sense to me
1f914.svg



It is not a stop screw, if the screw is used as such it will sheer off. That hole is intended for a peep site, the screw is just there to plug it. Yes most are missing because they are removed to scope it and never get put back in or lost. I put mine in a bag and label it in case I want to put it back in later.


I believe this is the correct answer because I have observed that it does indeed sheer off when used that way.

Now that does make perfectly good sense.