I had it happen another time when I shot a turkey with my 10 ga. The turkey came in....went behind a tree I picked up had a relaxed 'loose hold' on the hammer gun and touched the front trigger both barrels let off....250 grains of black powder felt like a car wreck.
From now on I shoot the rear trigger first turkey hunting.
Fortunately when I hunted turkeys with a NID 10 gauge (3.5"), it never doubled. While I only had about 100 total grains of smokeless powder, I was handloading 2 1/8 oz of lead in the left and 2.5 oz. spreader load (my Claymore mine load) in the right--1,998.56 grains of lead. It would have nailed me through the tree had it doubled.
