beer cans do not work "just as well" because it does not show you the whole pattern. you may be off a couple of inches and be able to move your sights to get a better poa/poi.

according to my way of thinking and patterning my gun is good at 50 yards and will kill 100%. but I still use it as a 40 yard gun. if by chance I happen to misjudge then I have a solid 10 yard buffer.

my gun went 6 for 6 this year(I killed 4 and my bud killed 2) all inside 45 yards with hevi 7s 3in 2oz.

as for what was said about KE from the 20 gauge of Adrian's. it does not matter if the shot is from a 410 or a 10. if the pellets are the same size(6s) and the velocity is the same then the per pellet KE is the same.