I was watching an episode of Law & Order in which someone was shot with a TEC-9. The ballistics expert said "TEC-9...unsurpassed for penetrating steel doors". I have never even handled a real gun so I know very little about them beyond TV and documentaries. Could two different firearms affect the penetration characteristics of identical bullets? All I can think of is:
- The rifling would add more or less spin altering the trajectory due to aerodynamics.
- The length of the barrel would affect the amount of time the expanding gases will be accelerating the bullet.
I could understand these two making a difference when either shot over a long distance or by weapons with vastly different barrel lengths such as a handgun vs a rifle, but not at short range between the relatively short-barrelled TEC-9 and any other handgun.
To effect the penetration they would have to be moving at a different velocity. Surely this would be governed by the amount of energy being used to push the bullets out of the gun barrels and this would ultimately come from the bullets themselves which are identical.
