whats the differance in knock down power from a 9 mm and 40 cal, or just in general between the rounds

If you hit what you're aiming at, not much. Just shoot what you shoot well and never look back. Don't get wrapped up in the caliber debate because as Chad has alluded above, it only opens a can of worms and the arguments never settle anything.

As long as it feels good.its good.
Thanks pretty simple.

9mm would be a great hand gun, not that heavy and recoil is manageable for newbies. 40cal is almost as the same with 45. I would say its in the middle.

Men shoot a .40 or .45. Little girls shoot 9mm.

Open a box of .40 and set it beside a box of 9mm. Which would you rather trust your life to?

In all seriousness, the bigger calibers pack more punch, period.

Bingo!

Here is an excerpt from a www.policemag.com article.

"The ultimate stopping power rests with your training with your weapon system. Accurate hits in any reasonable caliber will "stop" a person if that person has experienced enough brain or spinal cord damage to interrupt regular neurologic impulses from reaching vital areas of the body or the person has hemorrhaged enough blood to lower his or her blood pressure where the brain no longer is able to function well. You can also stop a person if a major bone shatters after a bullet injures it, but does that stop the fight?

Stopping power is a marketing tool and should be dropped from our discussions of ballistic performance until such time as ammunition effectiveness is measured by more means than just the results of gelatin and barrier tests. When ammunition companies or regulatory agencies begin to use computer simulations, simulant tests, animal models, autopsy results, and trauma surgeon operation reports with hospital summaries to determine the effectiveness of their products, then we will know which ammunition can be labeled as having the "best stopping power." And this claim will be based on scientific data rather than incomplete ballistic testing.

Until then, shot placement with any commercially available ammunition will offer you the best chance of maximizing your duty ammunition's stopping power."

The full article can be found here

^^What they said^^

This could rank right up there with .30-06 vs. .308, which elk cartridge, and HF vs. LF.

Ten miles of bad road....

From the ballistics the difference is not that significant. If you're going to shoot it a lot, the price difference certainly is. 9mm is significantly cheaper.

Or 1 1/2 miles of 3805!

After 7 months of rain...

By the way it doesn't matter if its 9mm or 40 cal what is important is the skill of the shooter for that precise target.

Get one of each.

Problem solved.

Tactical cowboy, you failed the troll test.

Don't you know you're not supposed to offer an opinion when an opinion is asked?

I like them both but think 9mm is so much cheaper to reload it makes sense to me.

The point is the question is not that great and is either uninformed or more likely authored by someone bored, wanting to see what kind of funny crap people will use as an excuse to post an opinion.

This time people made it fun to read and left most of the opinions to other areas.

If you load both cartridges to max, a 40 still has more power. This is just like the 9vs45 debate. I like a 40 because it makes Major in USPSA. Other than that, it really doesn't matter.

If you load both cartridges to max, a 40 still has more power. This is just like the 9vs45 debate. I like a 40 because it makes Major in USPSA. Other than that, it really doesn't matter.

I will say this from experience... when I went to police academy, we shot at heavy steel silhouette targets. The firearms instructor gathered us around the first day and told all the cadets, if you shoot a 9mm, you WILL HAVE to shoot the targets twice in order to knock them down. The 9mm just does not have the same terminal ballistics that the 40 and 45 have. The few cadets that had 9mms started to complain, but he told them to wait and see. Sure enough, the 9mm would not knock the targets down routinely. The 40s and 45s would knock it down first time, every time.

If you are shooting smaller targets (hogs, dogs, yotes, etc) it won't matter what you are hitting them with, but bigger stuff... bigger is better. I would highly recommend a high expansion hollow point no-matter what you are shooting. The wider it gets, the more energy it should transfer.

But all the cops are going back to 9mm

The ones around me aren't. 40 and 45 is the standard around here.

I think one thing is certain: ammo (or maybe more exactly correct, bullet design) has come a long way since the Miami shootout that prompted the FBI to push for the development of the 10mm and the subsequent development of the .40 S&W. I don't think I'd feel under-gunned carrying a 9mm these days, which I did for a few weeks about eight years ago, but I still prefer a .40 S&W or a .45 ACP. Bigger IS better...IF you can shoot it.

Yup... if you can't hit your target... might as well be throwing rocks.

Hit the steel in the right place and a MiniMag knocks it over, no? Leverage works better than brute strength. I'll take all three.

Uhhh...well, maybe NOT. I won't stand still whilst you lob those little .22 bullets at me though.

Ha!

Lob?

At you?

I'm coRnfused.

Are you made of steel?

Superman has posted.

Just kidding. I was only making a point, not trying to save the world nor was I being literal.

Happy Birthday to me.

Handgun calibers in question do not have "knockdown" power.

There are plenty of people that get shot in vital areas that do not drop on the spot and or do not stop their attack when shot with a 9mm or a 45acp. To drop someone in there tracks you would have to damage the central nervous system which can be accomplished with a 22 lr. Shot placement and training are the most important factors and if you are in a situation where you do have to shoot make sure you shoot until the threat has stopped.

The gun used in this video was a smith and wesson 40 cal. You can see the guy was shot 3 times almost point blank and ran away. He did die later but there was no "knockdown" power

https://youtu.be/f7ve6MhmeaY