The following is a from a thread started by the owner of Beartooth Bullets entitled "Teeth for the .410 Bore" with 4 00 buckshot balls:
"This load. out of the .410 shotguns we own here, will produce a neat, square pattern that is about five inches square with the four buckshot when patterning at 35 yards! *Not bad for a little .410 2 1/2" shotshell. *This load I described punches out the bore at about 1220 fps from our shotguns. *More fire under the charge just blows the pattern apart in my experience.
Now, about on target performance! *This load is really amazing when all four of those 44 grian pills impact a 4"-5" area at once on something the size of a 70-90 pound feral dog! *Out to 45 yards (farthest tested), it is lights out! *No recovered buckshot (remember these are fairly hard), and boiler room hits create nearly instant incapacitation, even on adrenalized critters of this size."