Bill:  Some Krag swivel screws were 'mushroomed' on the tip, after assembly, so that if they loosened up they would not fully unthread and be lost. - IMHO

(If it were mine, I would dress the threads at the tip of the screw with emery cloth or a small file.  Another option is to slightly enlarge the hole on the swivel.  These would be invisible adjustments).

Side-plate screws show up on ebay, often with a side plate, for around $15.  I believe S&S Firearms sells a reproduction screw for $5.