Hell, the muzzle blast on that thing alone would cook the duck too.
There uses to be a guy at Knob Creak, called himself "little fat man", he had two 1919's just like that. They we little more than shotguns.
Themao, the Germans never had proximity fuzes so I would go with a 40mm Bofors on a quad mount. Got to play on one at Pearl Harber last year, my wife could hardly pull me away.
On the other hand, the F.L.A.K. 88 has good depression and range so you can get them on the water at 2.5 kilometers.
Nice picture, too bad it got messed up so bad. That wasn't the most battlefield "flexable" mount
A good German air defence mount wouldn't be too hard to rig to work with the 1919. Post war mounts are lighter and cheaper and give a good 360 degree firing arc. But thats just what people tell me.