Hello Ron, I think those screws are 10-32, I might be mistaken but that sure seems like the size to me. You can get them from T/C or most likely from Brownells. If they are 10-32 your hardware store should have them at least in socket head style.
TC has them in two lengths for the front or rear screw on a 14 inch forend with the rear being longer.
I hope this helps.
Joe