9MM vs. 40 S&W

[Bryan5433]

I carry a Glock 26 and have been recently thinking about going to the Glock 27. How much more would I really be gaining as far as a knock down power and defensive round from 9mm to 40 S&W? Thanks for any advice you can give.

 

[Storm52]

Stick with the 9. I won't touch "knock down power". Keep your 26, put cash toward additional training and be comfortable knowning your weapon and your capabilities.

 

[chad]

9mm. Not as snappy, lots of velocity and just as lethal with modern day ammunition. 9mm expansion is pretty damn good. And more capacity. But I just hate the .40.

 

[Ben Segrest]

How much more would I really be gaining as far as a knock down power and defensive round from 9mm to 40 S&W?

You would gain negative one round of ammunition and slower follow up shots. Seriously, if you like 9mm, shoot that; if you like .40, knock yourself out. But it's not worth the effort to harp over which is better. They're both just pistols.

 

[Guate_shooter]

"knock down power" does not exist.

Newton's Laws of Motion (3rd) says "When two bodies interact by exerting force on each other, these forces (termed the action and the reaction) are equal in magnitude, but opposite in direction."

That means if a bullet has enough power to knock an attacker/threat down on his butt, it will also have enough power to put YOU on your butt on the other end of the equation.

NOW, penetration factors and muzzle velocity/force are things to consider.

 

[DAUC]

not to mention the price of 1k rds of 9mm compared to 1k rds of 40.

 

[Big H]

When you go to the hospital with a gun shot wound they do not ask whether you were "knocked down"/shot with a
9MM or a .40 caliber! Keep the 26 you already have and become proficient with it. That's my 4 cents worth(inflation)
anyhow----Good Luck

 

[Cochise]

not to mention the price of 1k rds of 9mm compared to 1k rds of 40.

This is what really makes the decision for me. Any good 9mm hollow point is more than good enough. Personally(read in my mostly uninformed opinion), the .40 shorty is a joke. I would really like to have a 10mm or a 357sig but realistically, I can't justify the expense of training ammo vs the limited practical gain.

 

[rrussotwo]

I'd rather have twice as many 9mm rounds to practice with.

 

[returningliberty]

Bryan, it's not really about "knock down power" at all. There is a negligible increase in kenetic energy between 9mm and .40, but not a lot. Enough to sacrifice 1 extra round of capacity and measurablly faster follow up shots? That's a personal question.
The .40, with the right bullet, arguably has more retained mass and slightly less deflection through intermediate barriers. Does that matter for a CCW? Up to you.

Personally, for a concealed handgun, I'd stick with the 9. For a full size "duty weapon" I would go with the .40, depending on what I was doing (possibly shooting through a windshield or what not).

 

[Guate_shooter]

A 9mm WILL shoot fine through Glass, we have done it in class without issues last one being the Talon Defense Class that Brannon, William (NOLATAC) & I attended. You just have to understand the angle in which it will deflect and be able to account for distance as well.

The more distance the more angle factor, at one car length there is about a 4-6" difference from POA to POI, then the angle of the glass + the angle in which the bullet hits the glass will dictate if its up, down or to any of the sides. Also tint on a window will make it act in weird ways and the front and back windshield are harder/thicker than side windows so I would take a side shot any day with less deflect than a front shot with high angle.

If you are worried about penetrating things go with .357Sig, its a good compromise among all calibers BUT the price to play with those rounds gets UP THERE.

If you want to really put them to test through a windshield while sitting inside the car NOLATAC is Hosting, Haley Strategic Disruptive Environments Pistol Class and there will be several vehicles to shoot though & at.

 

[GunRelated]

"knock down power" does not exist.

Newton's Laws of Motion (3rd) says "When two bodies interact by exerting force on each other, these forces (termed the action and the reaction) are equal in magnitude, but opposite in direction."

That means if a bullet has enough power to knock an attacker/threat down on his butt, it will also have enough power to put YOU on your butt on the other end of the equation.

NOW, penetration factors and muzzle velocity/force are things to consider.

While I like your way of thinking, I just can't agree with this. I would like to bet that a man that has been hit with a SD round from a 44 mag would definitely get knocked on his a**, while the shooter may take some recoil to the wrists, he will still stand. Furthermore, to go to the extreme side of the equation, let's say for example a man gets hit with a 10 or even a 12ga slug, would he NOT get knocked on his a**, while the shooter will still stand?

Now, I am not taking up for anyone who uses the term "knock down power", I am just trying to understand you point and see if we can come to an understanding on this physics equation.

 

[SGT_Kramer]

While I like your way of thinking, I just can't agree with this. I would like to bet that a man that has been hit with a SD round from a 44 mag would definitely get knocked on his a**, while the shooter may take some recoil to the wrists, he will still stand. Furthermore, to go to the extreme side of the equation, let's say for example a man gets hit with a 10 or even a 12ga slug, would he NOT get knocked on his a**, while the shooter will still stand?

There was a episode of myth busters on this.

 

[MikeR]

Movies are to blame for "knock down power" and the myth that people go flying when you shoot them. They don't, not even at close range with a Mossberg 590 loaded with military buckshot...thats from firsthand knowledge, not "read about" or "saw it done on Youtube."

To the OP, you are doing fine with what you have. Use the money for practice & training.

 

[GunRelated]

I wouldn't expect to see someone fly backwards through the air, but I would expect to see a large caliber take someone off their feet.

 

[MikeR]

I wouldn't expect to see someone fly backwards through the air, but I would expect to see a large caliber take someone off their feet.

Nope, and I hope you never have to learn firsthand that I'm right. The only thing that may cause them to jump is an involuntary reaction in the muscles...just like when you shoot a deer.

 

[BenCarp27]

Larger calibers and shotgun loads can cause a greater amount of damage and shock to the bodily systems. When victims fall back after impact, it's usually just a carry over motion from their movements prior to impact. Shotgun impacts can be slightly different, because the energy from the round is spread over a larger area than the bore. In most cases, however, a "knockdown" is simply a victim pulling or backing away from the shot, and then upon being severely wound, not being able to compensate for the initial motion and falling down. Or, they fall because their brain registers they've been wounded, and they simply "shutdown".
There are a lot of great and informative articles online that can explain it far better than most here can. A quick google search of "knockdown power" will pull most of them up.
Like most people, I used to be a firm believer in 'knockdown" power because that is what I was told and "witnessed". The more I study and read up on ballistic wounding, the more I learn I never 'learned' anything.

 

[Ben Segrest]

I wouldn't expect to see someone fly backwards through the air, but I would expect to see a large caliber take someone off their feet.

The easiest way disprove this notion is to look at deer hunting. When a deer is hit, it usually either drops where it was standing, or runs off. Sometimes they will kick or jump first, but they don't get moved by the bullet. A bullet with several times the energy of a pistol bullet.

 

[Guate_shooter]

Has anybody ever noticed a deer fly away 5 feet when shot with a slug or a pig fly away when shot with a 44mag? they were designed to stop animals that are not vertical but horizontal, their center of gravity is located in a different place and they have a lot of meat to go through before it hits vital organs. That being said people believe that if you shoot a human with this calibers they will fly on top of the roof of a house but that is far from reality, we have less mass to penetrate and out center of gravity is also located different than any 4 legged animal so INDEED they will create more damage/wound but at the same time we have less mass to stop the energy. Similar to shooting a 1/8 sheet of plywood and then shooting a 6x6 treated lumber and expecting the same result on both.

 

[Guate_shooter]

The easiest way disprove this notion is to look at deer hunting. When a deer is hit, it usually either drops where it was standing, or runs off. Sometimes they will kick or jump first, but they don't get moved by the bullet. A bullet with several times the energy of a pistol bullet.

LOL we had the same idea as I was typing