I have hunted ducks for many years.
I have never shot a bird with any type of firearm. I have shot a lot of rabbits and fast moving small vermin like stoats and ferrets and weasels.
I have two twin barrel over and under 12 gauge shotguns and one side by side twin barrel 12 gauge shotguns... all Russian, plus a Remmington five shot semi auto and a Japanese SKB five shot semi auto.
Was about to buy a Saiga or a Vepr but an immigrant ruined that for me by being a dick.
In terms of soldiers I would say a Saiga or a Vepr would be simpler and easier for Soldiers to learn to use and there is nothing inherently about a pistol grip or a box mag that means you can't shoot things in the air or small fast moving things on the ground.
Learning to lead a moving target is something you have to practise because it is a combination of distance and speed... faster targets and greater distances require more lead.
The video I posted above shows that at 35m even a short barrel Saiga gets the job done with a level of density which should get a few good hits with every pull of the trigger.
Shotguns don't work like lasers... it is not the case that a long barrel and a super tight choke will double the effective range and with different ammo types you really do have to test it because sometimes the spread of pellets is uneven and there are huge gaps in your patterns where nothing would get hit and you can't control where those gaps are.
Going to a lighter shot helps make the patterns more dense but also reduces the effect of hits too... and reduces effective range.
Really light shot as used in clay bird shooting has a huge number of pellets but wont cycle my semi auto shotgun because it is not designed for such light loads.