Lead deforms when it hits bone, slowing penetration.
And once deformed causes major havoc within the birds body resulting in more folded birds .
You are right lead is gone and gone for good, but from my experience heavy metal or steel with it's speed and penetration creates cleaner holes with less internal damage which results in more fly away cripples that end up dieing later too far to be retrieved. Any big game hunter will agree that the more deformed or mushroomed their bullet is when hitting meat and bone the faster the kill.
I agree with all other points though.
Since a lead pellet is already a mushroom onto itself, any further deformation tends to slow it's forward progress. Sectional density was explained by CP in his original post. A ball or pellet's sectional density is as good as it gets. Any deformation would lower it significantly.
A bullet mushrooming is slightly different in that it's penetration is based on limited expansion, weight retention and velocity with enouigh bullet shank below it to drive it forward and in a straight line. That comes straight from Jack Carter(inventor Trophy Bonded Bear Claw & Sledge Hammer bullets).
To compare shotguns to rifles shooting lead(apples to apples as best we can), we'd have to compare shotguns shooting lead pellet loads to muzzle loaders shooting round balls, not cylindrical projectiles.
High Speed steel sounds good, but the larger, lighter pellets lose speed quicker than denser pellets do. Keep in mind that higher muzzle velocity does not equal higher velocity at target impact.
A #4 steel pellet will lose it's velocity much faster than a #4 lead pellet if both are shot at the same velocity. Fortunately steel loads and many tungsten loads are loaded to much higher velocities.
Higher muzzle velocity does indeed equal higher velocity at the intended target providing that this target is kept within the intended range of the load being used.
If you're trying to compare a lead load to a steel load using the same pellet size, no contest.
If you compare a lead pellet to a tungsten pellet of the same size, no contest there either as the tungsten far out performs lead in every category: Retained velocity, energy and penetration.
Also, a 1 1/8oz steel load has the same amount of pellets as a 1 1/2oz lead load given the same pellet size. Most waterfowlers of the day shot 1 1/4 - 1 3/8oz lead loads because that is what was available. Most steel loads offer a higher pellet count than their older brother in a lead load. Many of today's super charged 3" loads surpass their older lead counterparts. Not to mention the 3.5" loads available these days.
And as far as price goes, most things have gone thru the roof in that regard. Shotgun shells are still darn cheap.
As far as mystery metal in Hevi-Metal shells goes: Hevi-metal is 50% steel, 50% Hevi-shot by volume. Not by pellet count. The ratio is even better because it's loaded with Hevi-shot two sizes smaller than the steel shot it's sitting on top of. That means that there are a lot of lethal pellets at close range and when the steel pellets slow, the Hevi-shot pellets will continue to be lethal and not hindered by the steel pellets. This info is on their site.
Check out all the info on this link:
http://shotshell.drundel.com/steel.htmTake a look at this chart comparing pellet energy. Steel pellets need to be about 2 sizes larger to match lead energies. Since steel is available in much higher velocity loads than lead can even be loaded to, I'd have to say that the good old days of lead(I started hunting ducks in 1968), killing ducks at unimagineable ranges, deader than dead, is mostly in our heads.
