Originally Posted by scottyd2506
maybe so but that 135 in a 40 cal is has a sectional density of like 1.21. it is going to slow down like a parachute, once it hits the fat layers and muscle the bullet will likely be sub sonic through the vital organs. esp a larger built BG.
going super sonic through the vital organs like the 357 does seems to be key in the police saying of "lightning bolt effect" I'm sure it would kill as good or better ,but we want the extra shock to STOP the attacker
The 357 sig can launch a bullet with a sectional density of 1.41 at 1500 fps from a 4 inch bbl. with that kind of sectional density the bullet does not slow down much as it penetrates probably going 1200 fps through vital organs.
The 9mm 45 and 40 can NOT do this. I'm sure a skinny bad guy it might, but some of those 260-350 lb attackers have extra layers to go through and the Sig seems to be able to break the sound barrier inside of the BG vitals.
I wouldn't get too hyped up on thinking that a sectional density of roughly .140 and 1400 fps (now you bump it up to 1500 fps) is necessary shock and stop someone nor a bullet having to remain above the sound barrier while inside the person. By nature, such stats would always benefit the smaller calibers because the bullets can be lighter while retaining a certain sectional density.
A .40 cal 135gr @ 1500 fps vs. a .355 125gr @ 1500...who really cares, both will be more than lethal. The Sig is going to be a little better breaking through hard objects and will penetrate a little deeper, but of those two, the 135gr is likely to open more violently, doing more damage. Sectional density is a factor, but it's not the only factor in performance.