A couple days ago someone started a thread about B-24 bombers. I thought those who participated in the thread might find this website interesting.
There's a photo of what looks like a Model 12 mounted on a tri-pod on the back of a truck, to help with training to shoot from a moving vehicle.
Also there's several pages from a phamplet reminding gunners that when attacked from there rear, since their bomber is moving away from the attacking enemy aircraft, they needed to aim behind the attacker rather than in front. Try figuring out that lead!