Thinking back many years, my best kills to cartridges ratio (7 birds for 9 cartridges) on winged game was with a single shot.
It was a little BSA .410” bolt action, one of those made using Lee Enfield bolts in a simplified tubular receiver, and with a Long Lee Enfield style safety on the cocking piece.
It had a 23” barrel, but the bolt mechanism made it handle like a 30” gun. They did a de-luxe version with a top tang safety.
2 1/2” chambered, it killed well with Winchester 1/2 ounce loads. Admittedly the birds flighting into a wood were not long range shots.
