Lead shot vs steel: The Field's guide to the ballistics

Lead has been used for centuries to deliver a clean kill. What must a gun know before deciding on its replacement?

- SIMON WEST

The organisations that represent live-quarry shooting have said that they want to move away from the use of lead shot over the next five years. Quite an ambition, and something some gun and cartridge manufacturers have been working on for years. But is it attainable within the limits of science and today’s guns?

Hitting a bird with enough energy to produce a clean kill is the core skill of every shot. In the game shooting world, lead has been the projectile of choice for centuries. It is dense, soft and cheap, and a perfect material to transfer energy from gun to target. But, as we now know, its chemistry has a harmful effect in living organisms. That evidence obliges us to look for alternatives to reduce the overall effect on our environment. So, what else is available to do the job?

To produce that clean kill, we need to fire enough shot with enough energy to provide coverage and penetration. That combination of pattern and lethal energy transfer is the collective responsibility of gunmaker, ammunition manufacturer and shot. Almost all our guns have been designed around lead shot as the primary projectile but that doesn’t mean we can’t use other materials, if we provide coverage and penetration.

So, what are the options? Physics reminds us that kinetic energy is reliant on velocity and mass.

Velocity depends on the gun and propellant accelerating the shot load along the barrel. For that we need pressure and that brings us to our first challenge. Modern guns, with modern steels, can be manufactured to work at very high pressures. The superior service pressure to which they are designed is 1050 bar (~15,000psi). Older guns are only designed for standard nitro pressures of 740bar (~10,000 psi). There are also proof limits for some ammunition on velocity and momentum; but more of that later.