I have a semi-auto Thompson 1927A-1 (sorry it's not NFA but I didn't know who to ask) with the adjustable ladder type rear sight. I don't know the distances for the increment marks on the ladder and would have to shoot a shit load of ammo to figure them out. Can anyone help? Does anyone know how many yards correspond with each mark?
Any help you could provide would be greatly appreciated,
MadDog