The pattern of the shot degrades quicker than the velocity.
Badger - well put!
As Badger stated, shot deforms. Harder shot resists deformity better. Copper plating For instance resists even more.
Steel shot is less dense , tho harder, , hence ALL the headache on non toxic shot on Waterfowl so many years ago. We had to go up at least 2 shot sizes to obtain the penetration and effectiveness. with had with lead.
[arrgghh...]
Most folks only read a pattern board thinking about pellets on the board.
Not all shot arrives at the same time - "stringing".
Tho not so critical for Buckshot distance,...but consider the stringing in a Duck flying 30 mph and that distance, the shot does not all arrive at the same time...so "what shot is arriving at what energy at what distance to kill duck"
vs two / 4 legged critter moving say at from your kitchen/backyard through the hallway/property ....there will be some buckshot arriving sooner than others...not as much shot ( 9-12 pellets for instance) principle the same.
See why Buckshot and game at distance is not always a HOLY GRAIL ?
In a "perfect world" all Buckshot would arrive at same time - no shot strings, not even short shot strings...much less the vertical/horizoantal string.
"Something gotta deform /give".With Steel Shot
Well too tight a choke and bbls bulged at muzzles. Some forcing cones ...were "altered".
I personally think at time we need to quit "fixing stuff". IIABDFI
WE speak of pattern boards - stationary teaches us a LOT.
MOVING pattern boards teaches us LOTS MORE.
Bob Brister did some studies in his book.
Tell you what take a garden hose with a sprayer, "pattern" the spray. Hit the trigger and release...not all water arrive at the target at same time.
Now if you had a moving target- and repeated hitting the trigger and releasing- this really becomes an eye opener.
"You can't miss with all them pellets" - Wanna Bet?
"You can't miss the neighbor"s pet running through the yard with a full spray " Wanna Bet?