Hello! New here but not new to guns. I recently inherited by father-in-law's Tanfoglio TA75 .22 revolver. A screw is missing; one of two right aft of the trigger guard - don't know what they're called or even what they do. I suspect the gun has been used for years without it but I'd like to replace it. I've tried the Gun Garage in Arkansas and Lee's in Texas but neither could help me. Sure appreciate any help; thanks!