RE: 1940 winchester model 12 12 gauge ammo question?
As long as you use lead shot you will be fine...This includes buffered, copper plated lead turkey loads.. Federal Premium or Win XX turkey loads would be good choices...
Some of the non-toxic shot, such as bismuth, can be used also , but the lead loads will be cheaper, and will kill turkeys just as well as they did years ago, back when lead shot was the ONLY option...
Avoid steel shot as well as some of the harder non toxics...