In Finnland buckshots are allowed but not for larger game than roedeer. I use to carry couple of 4 buck magnum on my cartridge belt just in case. When trackin a wounded animals I quite offen use shotgun or combi and quite often there is buckshot in the other chamber. When use combigun on wounded moose I never use buckshots.
When I have to use buckshots I prefer quite open chokes like imp. cylinder or modified because they do the tightest patterns on my guns.