dsh,

Your weight comparisons are useful, but you are forgetting three primary components to knockdown/killing power. 1) Density, 2) Force, and 3) Aerodynamics.

First, although the XR's are approximately the same weight, they are propelled at slightly higher speeds and are more dense. By keeping the weight the same, but increasing density, this equates into more momentum (ie 3x denser pellets hitting the same surface area) with greater force. Remember, density does not equal weight---think about it this way---would you rather be struck by a 1 pound pine board or a 1 pound piece of oak? If the boards are the same shape, I'd much rather get slammed with that "soft" piece of pine...same theory applies here with the density comparison of the shot. Or 1 pound of feathers compared to 1 pound of lead weight dropped on your foot? One pound may equal one pound, but the difference in density will be directly correlated to the amount of downrange force.

Secondly, the force of the pellet is not lost upon impact, because the greater density of the tungsten composite does not undergo conformational shape changes upon hitting the target. Lead not only loses downrange velocity but also flattens upon impact, thereby greatly reducing the force, or what we refer to as "knockdown/killing power". Therefore, penetration will be greater at longer distances, with shot that are more dense.

Thirdly, the "hevi-shot" type loads also produce better aerodynamics, simply because the shot are more uniform and maintain their shape when propelled thru the muzzle, whereby lead shot is already being mis-shapen before it ever encounters the downrange target. Hence, not only do the hevi-shot type loads produce more killing force, but they also pattern better because of their improved aerodynamic stabilities...