[82nd ABN]

I am pretty sure that is a roll pin and not a screw. You need to take the action out of the stock and tap it out from the bottom side of the receiver. When you pop the action out of the stock look at the other end of where you would think the pin would come out. I have an old gen III SAI mount and it is not a screw its a roll pin nor is the hole threaded. I am pretty sure it a 1/8 inch roll pin punch that you will need. Let us know how you make out. You may be able to reuse the roll pin that you remove if its not too loos when you go to put it back in.
I take it you are referring to this hole?

When you punch it out from the bottom remove the scope mount piece off to the left and install the guide from the left.

 

[tostado22]

Well I feel dumb haha. I need to get a punch set anyway so I'll pick one up tomorrow and try that out. Thank you