More Powerful, 9mm or 40 caliber?
- Thread starter metweezer
- Start date
Were you from Homi?Bartholomew Roberts
Moderator
All energy represents is the potential to do work. It is the type of work done with the energy that matters. The person in your ER wasn't killed because of mystical waves of energy radiating off the golf ball. He was killed because the impact damaged his brain physically in some fashion. There may not have been a cavity in the sense of a bullet cavity; but there was definitely physical damage.
Same thing with bullets. A bullet with 600 ft/lbs of energy that delivers all of its energy but doesn't hit anything vital will be less effective than a bullet with 300 ft/lbs of energy that penetrates the heart. The energy itself is only a rough measure of the work potential of the bullet.
when it comes to 9/40/45, energy delivered makes no difference. none of these will "knock a man down".
the energy these calibers delivers simply equates to a small temporary wound cavity that reforms around the permanent one.
penetration and expansion are what counts (along with shot placement, of course).
MashieNiblick
Moderator
Generally speaking, the major factors involved with overpenetration are:
- bullet diameter
- bullet weight
- bullet velocity
As bullet diameter increases, penetration decreases.
As bullet weight increases, penetration increases.
As bullet velocity increases, penetration increases.
Very easy to find a heavy bullet weight 9mm + P that would penetrate more than a light weight, low energy .40.
Conversely, also easy to find a light weight bullet 9mm round that would penetrate much less than a heavy, high energy .40 bullet.
Generally, .40 bullets are heavier, therefore the recommendation regarding use of such caliber in woods or brush.
- bullet diameter
- bullet weight
- bullet velocity
As bullet diameter increases, penetration decreases.
As bullet weight increases, penetration increases.
As bullet velocity increases, penetration increases.
Very easy to find a heavy bullet weight 9mm + P that would penetrate more than a light weight, low energy .40.
Conversely, also easy to find a light weight bullet 9mm round that would penetrate much less than a heavy, high energy .40 bullet.
Generally, .40 bullets are heavier, therefore the recommendation regarding use of such caliber in woods or brush.
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Sectional Density
Read the first couple links, and that should give you a good idea.
I used to be very confused back in the day as to why lighter, faster bullets with more momentum and more energy always penetrated less than their heavier counterparts. Then I heard about sectional density.
Check it out!
Read the first couple links, and that should give you a good idea.
I used to be very confused back in the day as to why lighter, faster bullets with more momentum and more energy always penetrated less than their heavier counterparts. Then I heard about sectional density.
Check it out!
imthegrumpyone
New member
Have a sweet shooting 9mm, but carry one of the two .40s I own only. The 9mm sits in the closet for extra fire power. 
skydiver3346
New member
9mm or .40?
I just skip the .40 and use either the 9mm or .45acp. To me, that certainly differentiates the two from each other as compared to 9mm vs. .40 S&W.
Actually I really like both of these calibers and believe it or not, the .45acp seems to have a little less recoil than some .40's I have shot....
I just skip the .40 and use either the 9mm or .45acp. To me, that certainly differentiates the two from each other as compared to 9mm vs. .40 S&W.
Actually I really like both of these calibers and believe it or not, the .45acp seems to have a little less recoil than some .40's I have shot....
More powerful? If you look at kinetic energy or look at momentum, generally the .40 S&W is marginally more powerful.
Recoil: if the mass of the weapon firing the two cartridges are the same, the more powerful round will impart more energy to the firing platform which will be felt as more recoil by the shooter. (For example, if you could convert a handgun from 9mm to .40 S&W)
What does that mean in terms of incapacitating a human threat? Very little, if anything; compared to the skill of the shooter and his/her ability to place accurate shots to center of mass quickly in a life threatening situation.
I am not familiar with any evidence to support your LEO friend's assertion. It would be helpful to know what is meant by over penetration. Is it a bullet that has passed through over 12" of the torso of a human threat or merely 4 inches of a limb without hitting a bone? Is it a bullet that has passed through two interior walls without hitting wood? I have read the first 5 years of published FBI ammunition tests and have perused the Box of Truth website . . .
As to over penetration:
Since 4 times as many bullets miss the intended target in a defensive shooting situation as those which hit; the consideration given to "over penetration" seems wasted. If it is determined that of those bullets that actually hit the intended target, say 10% actually fully penetrate the target that makes the missed an even greater ration of all bullets fired. Instead of 4 to 1 it would be 40 to 1.
Focus on the much more important goal of quickly and accurately hitting the threat.
The .40 has more potential, if the shooter can shoot it as accurately and quickly as he can the 9mm.
The additional question is, can the shooter do that shooting not only from Weaver, Chapman, or Isosceles, but also one-handed and weak-handed?
If the answer is no, the 9mm might be the better option.
Oh, yeah, practice counts, too... if the shooter can't afford to feed his .40 (or .45, etc) at the range, he might also be better off with the 9mm. Muscle memory counts, especially under high levels of stress.
The additional question is, can the shooter do that shooting not only from Weaver, Chapman, or Isosceles, but also one-handed and weak-handed?
If the answer is no, the 9mm might be the better option.
Oh, yeah, practice counts, too... if the shooter can't afford to feed his .40 (or .45, etc) at the range, he might also be better off with the 9mm. Muscle memory counts, especially under high levels of stress.
