NRA is all about Rule of Law, except when it's something they don't like
(copied from a post at Bartcop's forum)
What is the big deal about replacing lead bullets?
Many states ban lead bullets for hunting but the NRA
has threatened to ignore the law:
http://news.yahoo.com/nra-condors-sorry-were-going-keep-killing-lead-214655160.html
These are the same people who espouse the "rule of law."
I guess the NRA thinks they are above the law...
= new reply since forum marked as read
OMG 
done here
Bullets (as in from a rifle or handgun) are generally solid chunks of lead with a copper jacket over most of the bullet. Lead is much denser than copper. It's also easier to form, and cheaper.
Copper bullets are much lighter for the same physical size than copper/lead bullets, so they slow down faster. They arrive at the target with less energy, and their trajectory is curvier than the equivalent copper/lead bullet.
You need a longer bullet to achieve the same bullet weight. And since there's a physical limit to the length of the bullet, it also reduces the upper limit on bullet weight.
There are other, more technical reasons... copper is harder than lead, so the bullets don't move down the barrel as well, which can lead to pressure spikes in the gun as the burning gunpowder tried to force the bullet (which is slightly larger than the barrel, in order to form a gas-tight seal) out. A longer bullet adds to the problem, as there is more friction surface.
Some companies make what are called "total metal jacket" bullets, with the lead entirely surrounded by copper, but the bullet might not retain integrity if it hits something really hard, like bone or rocks.
It's probably not that big of a deal, but it's an issue. Hunters, when they find something that works well, don't want to risk a bad kill or a runaway, injured animal, with something new and untested.
Shotgun shells are different. One alternative is steel, which is less dense than lead. Because it's less dense than lead, you need to increase the size of the shot pellet to get equal performance. But if you increase the size of the shot pellet, you get fewer pellets per shell, making your cloud of shot thinner. The rule of thumb is to increase the shot size by 2. If you like to use #4 with lead, use #2 with steel.
Some older guns have barrels that aren't built to shoot steel; the harder shot damages the barrel. But both of the problems can be overcome using a modern shotgun that takes longer shotshells, like the 3½" ones. Longer shells have more room to hold more steel pellets to make up for the previously mentioned problem. Lead shot is typically found in 2¾" or 3" shotshells
Another alternative is copper, which is about as dense as steel, but softer. Same shot-size problem, same solution... shoot longer shells.
Yet another alternative is some sort of bismuth alloy. This is denser than lead, so it's actually better, but it's expensive.
Considering that California like to pass laws just to discourage gun ownership, the NRA's position is probably just being reactionary, as usual. Or they're trying to just stir up some bullshit again.