I have fired hundreds if not thousands of rounds of buckshot- mostly in official capacity. In a standard police shotgun (Rem 870 with no work done to it) I could not reliably get all 9 pellets to hit inside the scoring lines on a TQ19 at 15 yards. If you did a long forcing cone you could keep them in at 15. There was a guy, Louis Aurback or something that had a system with a really long forcing cone that would let you pattern pretty good to 25 yards.
Fast forward to shotgun hunting. I played with many different loads and choke tubes. Generally, buckshot does not like a tight choke. A long modified is as good as it gets usually. I never could get any buckshot to pattern good enough to want to hunt with it. I ended up using #2 hevi shot and BB hevi shot. They patterned enough better to be worth using.
When I did entries on search warrant and arrest warrany executions, I was often point with my 870 and I would either carry 000 buck or maybe slugs. Ranges were whatever you could get inside a house or apartment. It was close range stuff! Only thing I ever smoked with buckshot was a dog!
