Press the barrel up against anything, and that short recoil reciprocating barrel system won't work. I've had one fail just from leaning into it while the barrel rested on a barrier.
When I was in the Cavalry we'd practice shooting at styro RC planes and I can tell you hitting a flying target that small is very difficult, even with MG's. 00 buckshot might your best option assuming it's close enough; beyond that, a well aimed rifle.
Waging a ground war/occupying enemy territory as we know it is effectively over. There are electronic counter measures to drone attacks but they've definitely changed the battlefield. I dunno really what us Joe Blow citizens could do to counter them in a SHTF scenario.
Being able to capture it and repurpose it or connect a tracking device to it that then you can release back into the wild and do an old-fashioned T-Hunt or fox hunt as we call it in amateur radio. Then you can find the individuals who are controlling them. Or as I said hacking it and downloading the data that is on it or uploading a virus on it so when they connect it to their computers it will brick their system or allow you to put a back door into their network and boom you have control.
my preference are the vang comp elastic holders
https://vangcomp.com/product/vcs-detachable-side-ammunition-extra-carrier/
Just seem to have the best hold/release of any elastic ones I've used