I shot a flat of boss over a few seasons now I went with Kent. Winchester makes a bismuth now, although the weight of the shotload seems on the heavy side if you ask me. Stay away from any bismuth shells with the gimmick word "hevi" in the name. First off it's bad grammar, second they terrible shells. Still surprised Federal puts up with it.
I have had 3 squibs from my flat of boss shells. Not sure if it's moisture got in, or powder leaked out of the shell, or both. I've got a few where the crimp opened up a lot. I'll shoot those at clay pigeons.