Nope, Lyman and Redfield both made receiver sights for the 99's made after the 1,000,000 serial number. At 1,000,000 they stopped D&Ting the rifles for the tang sights and only drilled and tapped them for scope mounts. Although it might be easier for you to just get a Williams as the Redfields and the Lymans are few and far between if you can get lucky enough for one to show up on Ebay. They mount to the two rear scope holes. The extra screw your seeing is the "ejector screw" that is only on the 99C, don't remove it or your ejector is going to fall down into the mag well inside the receiver.
Here's a pic of my Lyman SB that mounts to the scope holes.
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