Good Morning Dave.
I've shot a fair amount of the various HeviShot products.
In fact, I just picked up 30 rounds of their densest in 2oz loads at $1.50 each!
I see no need to go too far in depth on this, but rather will just contribute to clarify your question a bit.
Heavy shot pellets are harder than barrel steel.
They have pellets that are denser than lead, and come in several product densities within the HeviShot brand.
They obviously group very tightly, and carry devastating energy far further than a similar lead pellet.
Look at the energy charts to see just how far out the pellets will fully perforate a bird. For the density you have.
Why?
Miss or shred up close, dia way out into the cattails as to be unrecoverable. Scratches in barrels after use.
My point was that regular Hevi Shot probably isn't the product you want it for.
Note: I cut up the 2oz turkey loads to get the shot.
