The 9mm vs 40 S&W vs 45 ACP debate has been raging for a long time. I can’t solve it for you, but I can give you the information you need to make an informed decision. But we need to jettison some pseudo-science first.
Kinetic Energy does not matter.
Seriously.
It has exactly zero effect of a bullet’s deadliness.
Don’t believe me?
A 490 grain Broad-head arrow traveling at 225 Feet Per Second (FPS) has a kinetic energy of 55 ft-lbs. A 1 pound gel filled bag launched at 60 FPS has a Kinetic Energy of 55 ft-lbs.
Exact same energy, but which is more lethal?
Its very simple and easy to understand how an attacker can be incapacitated. But it’s not with some mythical force called “stopping power” or “knock down power”. Consider this: Can you measure “Stopping Power” or “Knock Down Power”?
Seriously, how many “Stopping Powers” or “Knock Down Powers” does a 45 ACP have?
How about a 9mm or 40 S&W?
It doesn’t matter if it’s 9mm, 40 S&W, or 45 ACP; they all do damage the same way. So before I get into comparing and contrasting 9mm vs 40 S&W vs 45 ACP, lets spend a minute talking about how bullets ACTUALLY do their damage.
Wound Ballistics Basics
(try saying that five times fast)
Anyway…
There are only two ways a bullet can do damage:
#1. Permanent Cavity. (The tissue the bullet touches directly, which it crushes into oblivion. Basically the hole it leaves.)
#2. Temporary cavity. (Basically the tissue the bullet damages, but does not touch. Read my “Stopping Power” and The Simple Truth of Terminal Ballistics article for more details.)
Here’s the bad news: most handgun bullets can only create a damaging permanent cavity (hole). Rifle bullets can create a damaging temporary cavity and are far more deadly. But unless you have a rifle or very powerful handgun, don’t even worry about a damaging temporary cavity. (there are a few exceptions, which we will discuss lower down)
Pistol bullets only poke holes.
That’s it.
Yeah it’s a great line about a 44’s power. But Hollywood got something about guns wrong… Again. Surprise, surprise.
Pistol bullets – even large ones like the .44 Magnum – literally CAN’T knock a person off their feet. Smaller ones like 9mm and 40 S&W don’t even have a prayer of doing it.
They just can’t.
To inject some science into that statement, “For every action, there is an equal and opposite reaction.” That means that all the force the bad guy feels is also felt by the shooter (in the form of recoil).
Therefore, If a bullet can knock the bad guy down, it would also knock the shooter down.
Even 45 ACP bullets can’t knock someone off their feet. If you break major bones, they may be unable to continue standing and fall down. But they won’t be “knocked off their feet”. Worse, they might not be stopped, or even slowed down.
Don’t believe me?
Then read this article recounting a police officer’s encounter with a bad guy: Why One cop Carries 145 Rounds of Ammo on the Job.
No really, go read it.
I’ll wait here.
The officer’s pistol was a Glock 21 chambered in 45 ACP and the officer himself was:
“A master firearms instructor and a sniper on his department’s Tactical Intervention Unit, “I was confident at least some of them were hitting him, but he wasn’t even close to slowing down,” (emphasis added)
And this one too:
“I thought I was hitting him, but with shots going through his clothing it was hard to tell for sure. This much was certain: he kept moving and kept shooting, trying his damnedest to kill me.” In this free-for-all, the assailant had, in fact, been struck 14 times.” (emphasis added)
Here’s the clincher:
“no evidence of drugs or alcohol was found in his system.“
Pistol bullets can only poke holes.
They can’t knock people down.
Movies have been getting this wrong for years. A western draw is a perfect example. The slower shooter always stops like he’s struck by a bolt of lightning. For the most part, that’s pure Hollywood fantasy. (unless the bullet hits either the brain or spinal cord)
So What Does it Take to Stop a Bad Guy?
Answer: You have to poke the holes in the right places.
In the 9mm vs 40 vs 45 debate, you can’t forget this simple fact:
The only way to instantly incapacitate an attacker is to destroy or disable the brain. If you can hit the brain, it’s lights out. (The officer ended the gunfight with a few shots to the assailant’s head.) However, the head is a small and easily missed target.
Because the head is a small target, conventional wisdom says aim for high center of mass.
For once, conventional wisdom isn’t completely wrong.
You need to disable the brain to force an attacker to stop. The only real way to do that (other than hitting the head or spinal cord) is by poking enough holes in arteries that they blackout from blood loss.
There’s a whole host of arteries and veins – not to mention the heart – that are protected by the rib cage. Hit enough of them, and their blood pressure will lower to the point of forcing unconsciousness. However, even if you put a bullet through the heart they will still have 6-10 seconds of consciousness left.
6-10 Seconds in a LOT of time in a gunfight.
It’s plenty of time for them to return fire, attack you with a knife, or swing a baseball bat with bone breaking force. To make them stop, you need to disable the brain. To do that without hitting it directly, you need to hit large concentrations of blood bearing organs and/or arteries.
The best place to do that is high center of mass.
However, It requires proper shot placement to incapacitate ANY bad guy. Hitting the bad guy in the pinky finger with a 500 S&W Magnum is less effective than hitting them in the head with a 22LR.
Now that we know how to stop a Bad Guy, back to the debate…
In my opinion, 9mm vs 40 S&W vs 45 ACP doesn’t matter too much because they all poke holes around the same size. Yeah I know that sounds silly, but it’s true.
Check out the picture below.
Picture borrowed from The best choice for Self Defense Ammo – Pistol Ammo
Those are Winchester T-series hollowpoint bullets after expansion. They are commonly agreed as one of the best jacketed hollow point bullets around.
Notice how close the expansion is.
The difference between the 9mm and the 45 ACP is only .12 inches. Basically one eighth of an inch. The 40 S&W splits the difference exactly.
Now, lets say you were in a self defense scenario and hit the bad guy. Good for you. But lets say the bullet missed something vital, but only missed it by a tiny little bit.
If you were shooting a 45 ACP that landed in the exact same place as a 9mm, you’d only be half the diameter – or 0.060 of an inch – closer to the vital zone than a 9mm.
1/16 of one inch. That how much closer you’d be with a 45 ACP vs a 9mm.
With a 40 S&W, you’d be 0.03 of an inch closer than a 9mm. That’s only 1/32 of an inch (less than a millimeter) in a 9mm vs 40 S&W.
Yes I know, that’s only one type of bullet. So how about larger sample size?
Lucky Gunner did an extensive ammo test with over 100 different types of self defense hollow points. They listed the raw data along with gel pictures and video. I added the average expansion numbers for 9mm, 40 S&W, and 45 ACP and here’s what the number’s say.
- 9mm Average Diameter: ~.5
- 40 Average Diameter ~ .59
- .45 Average Diameter ~ .58
The total average difference is actually LESS than the difference between the HST pictured above. If you count expansions as being closer to a vital organ/artery (half the diameter.) then the difference is 0.060 with HST vs a 0.045 spread with Lucky Gunner Average.
To put that in perspective, that’s less than 3/64 of an inch difference between the largest and smallest according to the Lucky Gunner average. The individual bullet makes more difference than the cartridge.
Now look at the ballistic gel picture and how much everything is getting blown around.
Do you really think that tiny little size difference will matter that much?
I mean really?
In a certain sense it MUST matter because sometimes that TINY difference will occasionally allow you to hit something vital you would’ve otherwise missed…. assuming you shoot just as well with the larger caliber (and most people don’t).
I would give a TINY edge to larger calibers simply because their large diameter does occasionally make a difference. But I would only give them A TINY edge.
Follow the logic:
- If poking holes is about all pistol bullets can do.
- And if 9mm, 40 S&W and 45 ACP all poke holes around the same size
- then they should have about the same effectiveness. (with a very slight edge to the larger bullets)
Here’s the data to back up that logic:
An Alternative Look at Handgun Stopping Power.
I pulled some relevant data and compressed it to a single table:
| 9mm | 40 S&W | 45 ACP | |
|---|---|---|---|
| Average number of rounds until incapacitation | 2.45 | 2.36 | 2.08 |
| % of people who were not incapacitated | 13% | 13% | 14% |
| Percent actually incapacitated by one shot (torso or head hit) | 47% | 52% | 51% |
A few things to point out:
- All of our cartridges took more than 2 shots on average to stop someone. (though the 45 ACP was close to needing only 2.)
- Their failure to stop rates were all within 1%.
- Their one shot incapacitation rate was within 4%.
So if you compare the actual 9mm vs 40 S&W vs 45 ACP “stopping power” (incapacitation) numbers, it boils down to a measly 4%. Like I said, I’d only give larger bullets a TINY edge.
It’s probably closer than that because of the effect being shot sometimes has on people. Again from the same article:
“In a certain (fairly high) percentage of shootings, people stop their aggressive actions after being hit with one round regardless of caliber or shot placement. These people are likely NOT physically incapacitated by the bullet. They just don’t want to be shot anymore and give up! Call it a psychological stop if you will. Any bullet or caliber combination will likely yield similar results in those cases.“
So in most self defense scenarios, a 22LR is just as effective for making bad guy give up as a 45 ACP. I’m not recommending you carry a 22LR, but remember that almost any gun will do it most of the time….
I’d recommend 9mm as a minimum, because smaller bullets don’t really have the penetration and expansion 9mm has. One or the other separately, but usually not both. However, I’ve recommended a few people carry .22LR because they couldn’t hit the broad side of a barn with anything else.
EDIT: I recently wrote an article titled “How Many Rounds Do I Need For Concealed Carry?” I included a study about police officer hit rates and the FBI’s opinion on 9mm vs 40 and accuracy. That resulted in some interesting numbers on how many rounds it takes from each cartridge to stop an attacker. So 9 vs 40 vs 45, which do you think took the most rounds? The answer might surprise you…
9mm vs 40 S&W vs 45 ACP Conclusion
I don’t really care which one you use as long as you are accurate with it. They all poke around the same size hole and have around the same effectiveness. Therefore, what matters is Where you poke that hole.
Hitting someone in the pinky finger with a .500 S&W Magnum is less effective than hitting the head with a 22 LR. You’ll see me say this all the time: NOTHING trumps shot placement.
Nothing ever has, nothing ever will.
The famous western lawman Wyatt Earp was renowned for his skill as a gunfighter. He has this to say about accuracy.
“Fast is fine, But accuracy is final. You must learn to be slow in a hurry.”
Wyatt Earp had gunfights with faster men many times, but he always came out on top. Why? If you read more about him you’ll discover he always took time to properly align his sights before pulling the trigger. Even at a distance of only 5-10 feet.
I found an interview with Wyatt Earp if you’d like to read his thoughts on gun fighting. It’s well worth a read but spoiler alert: his theme is basically this:
NOTHING trumps shot placement.
I’ve said it before: you can’t miss fast enough to win a gunfight or fill a hunting tag.
That statement is borne out in my carry choice. I carry a 9mm for two reasons. Reason #1 is because I shoot 9mm better than 40 S&W or 45 ACP. Reason #2 is because 9mm ammo is cheaper than 40 S&W or 45 ACP, so I can practice more for the same money.
I would recommend you carry whichever you shoot the best. It doesn’t matter to me if it’s 9mm, 40 S&W or 45 ACP.
What matters to me are rounds on target.
If you don’t have a pistol yet and/or are trying to decide what caliber to carry, I would recommend firing them all and then deciding which you shoot the best and are most comfortable with. If you have gun loving buddies, you could ask to try their pistols out. Failing that, rent some at a local range.
Fire them all, and pick the one you’ll shoot the best.
Remember, they all poke about the same size hole. So pick the one you shoot the best or that you feel most comfortable with. Again, I don’t really care about 9mm vs 40 S&W vs 45 ACP.
It doesn’t matter to me.
What DOES matter in a life and death situation is accuracy.
I carry a 9mm because I shoot it better than the 40 S&W or the 45 ACP. Pick the cartridge you shoot the best, then spend a lot of time practicing. That’s what will make the difference.
And there’s one more thing….
How to “Cheat” the Normal Rules of Handgun Wound Ballistics
The winning formula for hunting or combat is this: Great accuracy + Great bullets = Win. This section isn’t about cartridges, it’s about bullets.
I’m a firm believer that “If you find yourself in a fair fight, your tactics Suck“.
That’s why I don’t carry “fair” ammo. And by fair ammo, I mean the same Jacketed hollow point bullets used by 95%+ of the people who carry concealed.
There’s better options these days.
The vast majority of handgun bullets can only poke holes. But there’s a few extremely well designed bullets that can do more. Sometimes a LOT more.
My current carry ammo is the 9mm Polycase ARX. It was recently picked up by Ruger and is now usually sold as the Ruger ARX. I intend on changing to the Lehigh Defense Extreme Defender (NOT the Extreme Penetrator) when my budget allows.
I won’t into the technical details, but they allow you create a MUCH larger wound that is possible with conventional hollowpoint bullets. Additionally, since they don’t rely on expansion there’s no real possibility of them failing to do their job.
The Military Arms Channel did a great video on the Lehigh Extreme Defender’s performance. The comparison was with the Federal HST.
So, my solution to the whole 9mm vs 40 S&W vs 45 ACP debate was to carry a 9mm because it’s what I shoot the best. Then, I picked ammo that allows my 9mm to create a wound larger than a .45 ACP hollowpoint.
That’s what I call a win.
If you find yourself in a fair fight your tactics suck. So don’t get caught in a fair fight.
I use “unfair” ammo, but NOT because I want to kill someone. That’s the LAST thing I want to do. I carry that ammo because IF I am ever attacked, I want to survive. I pray the only time I ever draw my carry pistol is at the range to practice. But if I’m forced to defend myself or others, I want the odds stacked in my favor.
So wherever you fall in the 9mm vs 40 S&W vs 45 ACP debate, remember one thing. The winning formula isn’t using cartridge ABC or XYZ. The winning formula is Great Accuracy + Great Bullets = Win.
I have an aging .45 and decided on a new pistol was contemplating another .45 but licensing would have been somewhat tricky so decided on .40 S&W Glock 35 Gen 4. This I did 26.10.2016, paid up front and licensing in progress. Had I only read your article, which to me makes sense, I would have gone for a 9mm.
Regards
If you really want a 9mm instead, you could do a conversion. You’ll need to change the Barrel, magazines, recoil spring assembly, striker, extractor assembly, and ejector (which means the trigger mechanism housing), but it’s doable. Of course, That’s a fair few parts an G34 barrel alone will run you around $150.
Just a thought.
You are forgetting penetrating distance. The FBI has standards for that which includes the “shootee” wearing thick clothes such as parkas or tough leather jackets. I read many NATO personnel claimed that the 9mm was marginal and wanted something stronger. Can a 40 break the rib cage and hit the heart?
A 40 can do it easily, but so can a 9mm or 45. Further, all three can do it through the FBI “heavy clothing” tests.
If you read the FBI’s Justification for going back to 9mm, you’ll notice these three paragraphs.
And
And also
As for NATO issues with penetration, I haven’t seen that anywhere and all the test I’ve seen indicate that FMJ projectiles that NATO uses usually result in extreme penetration because they are non-expanding. (which makes perfect sense)
If by “NATO personnel claimed that the 9mm was marginal and wanted something stronger” you mean it’s ability to wound/stop the enemy, then you are absolutely right. ALL pistol bullets (unless you have a fairly powerful magnum) stop people pretty poorly. The bag guy not stopping after 14 rounds of 45 ACP hollowpoints is only one proof of this. There’s a LOT out there if you do a Google search.
Yes the 9mm is marginal, but so are the 40 and the 45. It’s why SWAT ditched sub-guns like the MP5 in favor of 5.56 rifles and shotguns. That said, any pistol is better than nothing, which is why I carry.
Excellent discussions… keep in mind that organizations that have to arm many people, such as the FBI, they have to use statistics to base their recommendations on (e.g., the 20-30% hit rate). But each individual is different as is each weapon. I’m pretty darned good with the Springfield .45ACP… not so much with the Ruger 9mm. So the discussion comes back to… if the goal is to stop the adversary from being an adversary then you (assuming you aren’t provided the weapon by an organization required to arm a lot of people) need to find out what weapon and caliber works best for you. If you’re hit rate is higher with the .45 then you might not need to fling as much lead to get the job done. The data sure seems to show that the ammo isn’t a major factor but hitting your target for sure is.
On that note, if you’re “flinging lead” please get to the range more. Practice saves lives.
So, find a range that rents guns or friends that shoot and see what works for you.
And youre right… “stopping power” is just a phrase not a data point and has no real meaning.
An arrow’s lethality isn’t based on kinetic energy, never was. It is purely based on cutting…Nothing else. A sharp broadhead that does not hit major bone will pas entirely through on most game. Its kinetic energy is meaningless and has absolutely nothing to do with its penetration on game. A broadhead must be sharp in order to cut organs, not push them aside which it would do if it is dull. The rest is based on bleeding and it is often far quicker than a well placed bullet to achieve its end. I’ve seen it and experienced it personally on large game.
For a bullet shot placement is crucial. However for a bullet kinetic energy is one of the most important factors as is bullet construction and good sectional density.
I agree with you that accuracy is primordial but not that kinetic energy is of no importance. A bullet is tiny compared to an arrow. If an arrow weren’t equipped with a very sharp broadhead but instead with a field point, it would still pass through but may not be lethal or may cause an agonizing death over a period of days.
Well first,
The pics of the bullets you called federal hst tactical shown is wrong ! Really bad when your suppose to have all this information about which caliber is best and you don’t know the difference between a federal hst and a Winchester t series.
Yes the bullets shown are t series. Yes wile all are close after fully mushrooming from the start of when the bullet starts to expand and travels 5 to 6 inches is much larger . So during this 5 to 6 inches the 45 being largest will cut a much bigger path than the 9 or 40.
I do agree shoot with what you can handle and shoot more accurately. And use the best ammo you can get. The lehigh extreme defender is a great bullet. And as you say it in 9mm leaves a larger wound cavity that a 45, that’s 45 hollow point. Now tell me the 45 with the extreme defender will not make a larger would cavity that the 9mm using the same bullet? If you can handle the 40 or 45 use them.
Fixed. Sorry for the mix-up and thanks for pointing it out. 🙂 In hindsight, I don’t know how I did that. Both the HST and T-series are very distinctive in how they look after expansion.
By far the best article i have read on the subject, thank you.
I live in NYS and max cap in hand gun is 10 rounds ONLY.
I’m thinking if I am limited to only 10 rounds, I might as well get the biggest bullet like the 45, thinking that it has a little better terminal ballistics in regard to “stopping power” than the 9mm. I mean, more rounds for 9mm is probably the biggest advantage but I live in a state that drastically limits ammo cap and doesn’t matter if it’s a 22LR, I’m still limited to 10!
Now, with this in mind would you guys still recommend 9mm over 45acp? Or that it’s still marginal difference so that it doesn’t matter?
To me, I or my wife can shot the 45 the same as 9. No difference in speed or accurately.
Please help. (For primarily home defense, especially my wife)
If you’re limited to 10 rounds max and truly shoot .45 just as well as 9mm, then the bigger hole always wins. I like 9mm because so many people shoot it better (including me) and you get high capacity. But since neither of those advantages apply to you I’d opt for the bigger hole. 9mm ammo will be cheaper for practice though.
Abe,
Thanks. That’s what I thought.
I respect your opinion, but like most, I believe you look at it the wrong way. There is a reason the military asked for its new pistol to also have a larger than 9mm caliber available. The Sig won out, but caliber as yet to be released, as the Sig that won is both a 40 and a 9 mm. In regards to your arrow vs gel bag, this is a very skewed and unrealistic argument. An arrow is designed to go through while ‘cutting’ as much as possible. The bag was not made to enter a body. Stopping power is measurable. The easiest way is to hang a target from a tree, shoot it and measure the distance it moves back vs other rounds.(I know this is not exact but is an easy visual you can do in your back yard). Outside of rifle rounds, non are going to knock you down. But imagine your a beat cop and someone happens to be wearing body armor(which is very common over seas, getting more common, although still unusual here) then the extra thump would come into play. Also, if you are shooting for home defense and are carrying a very good hollow point, if that hollow point does not go through the body, then you have dumped all that energy into the body and it again comes into play. A FMJ with transfer much less energy into a body than the G2 RIP round. This is why rubber bullets are so effective and hurt so much, they transfer 100% of their energy into what they hit. So, in summation, stopping power is real, but the key is the amount transferred into the target itself.
I have to respectfully disagree.
When the FBI went back to 9mm from 40, they released a report justifying the change. One of the bullet points in the beginning says:
and later in the article:
Setting that aside though, lets use your suggestion of hanging things from a tree in your backyard. I’m a lightweight at ~150 pounds right now. If you hung a 150lb sandbag from a tree and shot it with a pistol bullet, I don’t think it would move much. It can’t because of physics. A pistol bullet just doesn’t have enough mass to make 150lbs move very much. A Little yes, but not much.
I’ll start off by saying that having shot all three calibers for most of my 20 yr shooting career, I have my preferences. I like the .45ACP a lot. Mostly because it is the chambering for guns I shoot well (the Glock 21, and M1911) and because I like the confidence that gives me. That said, I carry a .40S&W Glock 23, and that round is one that I also shoot well and feel confident carrying. I shoot a 9mm well enough, but my aversion to the cartridge stems more from military experience, which restricted my ammo choice to only ball ammo. I will disagree with your assertion that kinetic energy doesn’t matter. Kinetic energy does matter, it’s just that it’s only part of the equation. Your example clearly shows that 55 ft-lbs of energy is enough to kill (in the case of the arrow) or stop (in the case of the gel bag). Hell, I can probably generate more energy with a punch or kick. Kinetic energy alone is a useless consideration, I agree, but how that kinetic energy is transferred to the target is important. The .45ACP is a bigger bullet, with more mass, and lower speed. It dumps more of it’s energy into the target in a shorter time frame than the 9mm, which goes faster and is lighter and smaller. You are absolutely correct that bullet choice and shot placement are the most important factors in a gunfight. Famed US Navy SeAL Chris Kyle said in his book, that he switched from carrying a .45 to a 9mm because he found that he was able to achieve better shot placement with the 9mm, and that was more important to him. I felt that it was necessary to state this stuff, as I do agree with you, but it seems we arrived at our conclusions by different means. I tend to chose bigger bullets because of the confidence I get from those rounds. By confidence I mean both my ability to shoot the round, my ability to place the round where I want it, and also the ability of the round to stay in the thing I want it in. 9mm is perfectly adequate, but I would rather not risk the over-penetration for which the 9mm is known. Remember Jeff Cooper’s laws of gun safety, particularly “Be aware of your target and what’s behind it”, .40S&W and .45ACP give me the confidence to know that I will only kill my target when I pull the trigger. Other than that, it was an informative article.
Well what if all you CAN carry is JHP due to legislation? Wouldn’t then .45ACP be better than 9mm?
Sorry, meant FMJ
Often the legislative prohibits expanding ammunition, not specifically requiring FMJ. In that case I would pick something like the Underwood Xtreme Defender (not the Xtreme penetrator) in 9mm because it produces wounds larger that a FMJ and doesn’t carry the same risk of over-penetration. If the law specifically requires FMJ then I would probably still take a 9mm because I shoot it better. But I completely understand carrying a .45 too.
Abe, I have LEO cousin of over 26 yrs of duty, his description of what he has seen in “how” an assailant “reacts” to being hit (by different calibers), is as follows.
9mm = like assailant is being harrassed by an adamant “horsefly biting him”. Allowing assailant to continue on with their attack/advancement.
.40 S&W (and .45 ACP) = like assailant is being stung by a nest of irritated “assholes with wings” (AKA: Hornets & Wasps), thus rendering assailant as giving up MUCH QUICKER (sooner) than with 9mm.
He was on an undercover local drug enforcement in his early years (before taking position he’s held for the 26+ years), and had been in many shootouts due to this (come on now, IN Flint, Mi., Lol! One of the highest per capita murder rates yearly). He is concerned about self defense with his EDC he chose, being forced to use 9mm for his ammo, and severely wished that his EDC was available in .40S&W.
When he goes to restaurants anywhere near the locales he has policed over his career, he searches for the “corner without a cavity” so that he can watch his own front “six” for possible former offenders he’s arrested who may recognize him and want revenge and not allow them a shot from behind.
His Sig P229(?) he loves, but he absolutely hates the 9mm limit in cal selection. When I mentioned extra capacity with 9 vs .40, his reply was “IDGAS, I’ll take the slightly lower capacity of a .40, as I know it will do the job in less shots”. << his exact words.
Just sayin'. To each their own, but I'll take his word on how the two larger calibers are more effective per "hit".
His opinion contradicts a lot of data from the FBI (see my response to several previous comments), but I’m glad he has something he’s comfortable with. Like I said, pick the one you like the best. 9mm suits me, but it doesn’t suit everyone.
“Therefore, If a bullet can knock the bad guy down, it would also knock the shooter down.”
No no no no no no no . . .
You’re forgetting three things:
1. A bullet’s energy is developed as expanding gas pushes it down the barrel, so the energy that *is* transferred through the gun to the shooter, is quite different from the energy transfer of the bullet’s mass as it hits the target.
2. When you shoot (I hope) you brace the force of recoil with your entire body. Your arms act as complex fulcrums to absorb energy while maintaining control. Also, about 15-20 pounds of mass (the arms) isolate that force from your body. Again, this is quite different from a bullet unexpectedly hitting a body.
3. When a hollowpoint bullet hits a body, it expands and transfers the energy of its mass into a much larger area than the bullet’s original diameter which again, is completely different from the energy transfer the shooter experiences.
If you watch top shooters (like Jerry Miculek) they don’t flex their arms at all while shooting. They keep them rock solid. The wrists might move slightly, but not much. Additionally, look at a 9mm or 45 ballistic gel video. The gel blocks wiggle a lot but they are hardly blown away even though those gel blocks don’t weigh much. (less than twenty pounds if memory serves)