It's sectional density. That's the real reason one would want .357SIG over a 135gr .40S&W. If you knew you would always be attacked by someone in light clothing with no barriers between you then yes it probably doesn't offer much over .40S&W, but if there is any kind of hard barrier involved like auto glass, car door, metal signage, or possibly even interior walls or doors, the .357SIG will deliver more energy to the perp on the other side.
The combustion of fuel being necessary for heating and cooking in the home, the right of the people to keep fire extinguishers shall not be infringed. - Alternate structural interpretation of the 2A (to protect the people from the state militia).
Last edited by G26man; 04-12-2011 at 11:16..