Rainy day here in Georgia, just back home and notified I won this beauty at an auction. I have a 57mm and 106mm ( 105mm) RR and was looking for a 75mm RR to complete the set. Not in my possession yet, but I am posting some pics for interest, comments, history, thoughts. I will post markings and better pictures when in possession. Years ago I had a complete Firestone 1945 M18 57mm RR sub cal to .50, shot it often, then sold it to the DDay museum in New Orleans ( one of my many mistakes in life), this time around, my growing "collection" stays with me and can be sold off when I give up the ghost....my charming wife will probably give the stuff away.