On Tue, 30 Dec 2008 23:08:24 -0800 (PST), Frogwatch
wrote:

OK, I hear that lead bullets foul barrels. Is this why they coat some
with copper? Why not coat shotgun shot with copper, its easy and
cheap?

Copper plated shot has been available for the best part of a century,
as has nickel plated. Neither easy or cheap, as is true of copper
jacketed bullets. For about 40 years shot has been fired in a plastic
pouch, and it never touches the barrel. Fouling is not an issue
however copper plated withstand the stress of firing better, that is,
they stay rounder. They are harder so of course they penetrate better,
as well as arriving at the target with more speed than softer,
deformed shot.