I'm a duck hunter before all else, and I've always had an interest in ballistics of shotguns. Where most just see holes, I like to take note of how the pellets performed. Where most only choose ammo that "kills" to whatever their satisfaction is, I like to figure out each component.
Today I noticed something I have never seen before. I was hunting a private slough, and there were other hunters 1-2 miles away on a local lake I could hear shooting, same as always. I rather quickly got my limit of ducks, and went in. Upon dressing the birds, I noticed a pellet under a breast of a greenhead mallard. Odd, I thought, as the shot was only 35ish yards. At that range, all of my #4 bismuth pellets should easily pass clean through the bird. Then I noticed it was quite large, bigger than #4. I took note, and saved it. Today I confirmed it is magnetic, it is a steel/iron pellet. It is .150", #2 size. It did not come from me, I have not shot steel shot in a few years now.
What I think happened, is the hunters on the lake had either taken a shot at a bird too far, or this was a far one that was accidentally hit. It happens more than you would think. Numerous times I've tried to shoot a bird, only to have one 3 back in the flock go down. This stray pellet was the only one to hit the duck as far as I could tell (besides a number of my own #4 shot). It passed through only the guts in the back half of the bird, and was certainly a fatal wound. It entered the right side, went through the breast (which is quite thin in the back), through the chest plate, through the guts, just barely through the chest plate on the other side, and was resting against the inside of the breast on the far side.
So what does this tell us about that shot? Not much. I don't know how far it was shot, I don't know what ammo was used. It could have been a poor patterning load, or it could have just as likely been an accidental hit. What it does do is make you wonder just how many ducks fly off wounded. I had one sunday. A duck I know I hit, I saw the feathers, yet it flew off as far as i could see. The problem there was due to a goose call, I had my 10 gauge with B shot in my hands. I did not have the pattern density I needed to make the shot on a medium size duck, which was on the long end, about 50-60 yards. If I had my #4 shot loads, that bird likely would have had pellets land in the vitals at that range.
It also makes me really appreciate my decoy spread, which is apparently good enough fool ducks that were shot only minutes before.