Re: extra action screw on savage mk2?
there should be only 2 screws, the one between the trigger guard and bottom metal, and the one on the bottom metal just in front of the magazine well.
those other bolts may also be "leftovers" form where previous bolt spacings were / changing from pre E receiver to the E receiver, and rather than retooling, just incorporated the holes and the round stock they already have to be used to keep the inerds together - keeps the price down too by utilizing what you already have on hand.
let's face it, other than some minor ejection port length changes (so they can use the same one for 22lr, 22mag and 17hmr) and the cutout for where the bolt handle fits, not much has changed with the savage mkii receiver itself.
if you have an "extra one" that actually goes throough the stock and connects the receiver, please post a picture as it's news to everyone.