Excellent post above already.
I just wanted to add that when I shoot trap I consider it practice for hunting. As such I use the load I'd use for wing shooting.
#6@1200/1250fps out of a modified cylinder choked 18" barrel.
I also snap shoot...
Makes the game a bit more difficult too but I typically bring down low 20s.
Oh and I buy my ammo from Walmart too.
This is who we are, what we do.