Looking for a replacement axle screw, can anyone help?

Hi everyone, I recently acquired this Pflueger Progress 80 Bulldog to restore it. When I went to go remove the axle screw, it snapped in half. I cannot seem to find any schematics, drawings, or parts lists to point me in the right direction for a replacement screw size. I’ve used thread gauges to assist me but every screw I’ve ordered based on the gauge has been too big. Does anyone have any information that could help me locate a replacement screw? Any and all information will help, TIA and tight lines!