I hope you’re ready for an argument. You’d probably have better luck changing someone’s religion compared to changing their mind on 9mm vs 40 cal. Unfortunately, most people, including large police departments, choose their preferred round based on anecdotes, and very limited data. For this article, we’re going to provide a plethora of sources so you can make an informed decision. Or you could just listen to Bud down at the gun shop, he seems cool. Keep reading for more.
My goal for this article isn’t to advocate for any particular caliber. I don’t think of 9mm vs 40 S&W as purely an either or proposition. I tend to think that each round has its strengths and weaknesses. Depending on what kind of shooter you are, one of these rounds should be better than the other. Take a look at this quick overview for both rounds.
9mm vs 40 Smith and Wesson Overview
- Stopping Power Isn’t Just Muzzle Energy
- Hollow Points Should Be Used Above Other Round Types
- Muzzle Velocity Isn’t As Important for Pistol Cartridges
- A Bigger Bullet Will Generally Work Better In Most Situations
- Psychological Stops are Just as Important as Mechanical Stops
- There Are Less 40 s&w pistols than 9mm caliber guns
- There Are No Rounds That Guarantee a One Shot Stop (Including Long Guns!)
These points should give you the gist of what we’re going to be talking about. In this article we’re going to be using some science, and some real world data, to give us an indication which caliber will be the best for your individual needs.
I know that most people reading this are likely dudes. As such, you probably have larger hands and higher overall grip strength. This really matters. As a general rule, a larger caliber bullet will perform better. To use a gross exaggeration, shooting someone with 155mm Howitzer would be more likely to stop them compared to a .22 pocket pistol. However it’s hard to come by Howitzer ammo.
This does illustrate the point. We need to be able to easily use the round in our pistol of choice. It must be easily controllable. Most importantly, it needs to do enough damage to stop an attacker! Now let’s talk about the terminal ballistics of stopping power.
Factors that Affect Stopping Power
As I alluded to above, stopping power isn’t as simple as saying a 9mm Luger has 300 ft/lbs of energy, and a 40 Smith and Wesson has 400 ft/lbs, so the 40 caliber wins. These numbers aren’t accurate, and they aren’t sufficient to point us in the right direction.
Succeeding in a self defense situation will require more than just picking a round that theoretically works better on paper. As you’ll see, there are a variety of factors that will give you the best chance to succeed.
First, your skill matters. Knowing when to shoot, how to shoot, and knowing the importance of shot placement will trump any mechanical advantage that a certain pistol cartridge will offer. The fundamentals of shooting matter more than any super bullet.
Should We Pick The Caliber That Law Enforcement Agencies Use?
This is a very common question, and I think we should certainly use their decisions as a metric to keep an eye on. It’s important to keep in mind that police departments, and federal agencies, have more considerations in selecting their bullets and guns than we do. However, in recent years, law enforcement agencies have started to transition from the 40 s&w back to the 9mm cartridge.
They have budgetary considerations that we may or may not have, and they have to be able to purchase large quantities of guns, gun parts, and bullets for training. There are amazing calibers that no department will issue due to logistical considerations. The 300 Blackout is a perfect example of this.
If you’ve read my article reviewing my POF Renegade Plus in 300 Blackout, you’ll know what a great caliber that cartridge is. It certainly isn’t as widely used as 5.56mm, and as a result, most agencies would never consider adopting that caliber, even though it’s arguably one of the best.
Bullet Weight
As a good rule of thumb, you should seek to shoot the heaviest handgun bullet weight for your chosen caliber. This is because there are two ways a bullet actually damages a person. The first way is mechanical crushing damage of the bullet displacing tissue. The second way is by creating a temporary cavity using a high pressure wave behind the bullet.
Only rifles can create a significant temporary cavity, because the bullet must be traveling at a much higher velocity to develop the required pressure wave. Sure, there is a temporary cavity for both 9mm and 40 cal bullets, but it’s a paltry thing compared to that from a high speed rifle round. This is an important factor why rifle rounds work better than pistol rounds.
We need to choose a heavier bullet because more of the energy from the bullet will be transferred to the target effectively. The only reason to accelerate a bullet faster is to try and create a temporary cavity. We can’t accelerate pistol rounds fast enough to do so. Here is a shot of the temporary cavity from a high velocity rifle cartridge.
Bullet Velocity
Those of you who remember high school physics might recall the equation for kinetic energy equals one half times the mass, multiplied by the velocity squared. This means that if you double velocity you quadruple kinetic energy, where as if you double the mass of the bullet you only double the energy. Given this, we should go for the faster lighter bullet right?
Not so much. If you were able to accelerate the bullet fast enough to create a temporary cavity, you might be on to something. Moreover, that temporary cavity would have to do more damage than the permanent wound channel caused by the bigger slower bullet. That isn’t so certain.
You would also have to increase the amount of energy you put into the bullet to accelerate it to that speed. Because momentum is conserved, the amount of force exiting the front of the pistol is equal to that going into your hand. You’ll find that increasing velocity directly increases recoil. At a certain point you just can’t hold onto a round that is that powerful. I bet you thought 9mm vs 40 was going to be a little simpler than this!
Hollow Point Selection: 9mm vs 40
This leaves us with inescapable conclusion that we need to create a larger permanent wound channel. While larger caliber handgun calibers will do so, that advantage isn’t so clear cut with modern hollow point rounds. Using the best 40 S&W hollow point cartridges will only give you a 23% bigger surface area than the best performing 9mm hollow point cartridges.
This seems impressive when given in percentages, but the actual differences are pretty small. A 9mm hollow point has an expanded diameter of .43 square inches. A 40 caliber hollow point has an expanded diameter of .55 square inches. I doubt any human could tell the difference when shot with either. Nor do I think anyone would volunteer for that experiment!
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Bullet Terminal Ballistics
Lastly, we need to discuss what the bullet does once it strikes a person. We know that we should use the heaviest handgun round we can find, but it must penetrate deep enough to affect the bodies vital organs. This is why birdshot in a shotgun isn’t a good home defense round. It has a lot of energy and mass, but it doesn’t penetrate very well.
The FBI protocol for ballistics gel testing requires that a round penetrate between 12-18 inches of ballistic gel. This insures that a bullet will enter the body deep enough to damage vital organs. More penetration is not better, as shooting through a person only endangers other people, and does not increase stopping power.
We also need to consider how reliable the hollow point round is. Some hollow points will not expand when shot. They can become plugged with clothing, or other debris, and then they will act just like a normal ball round.
All of this means that we need to pick the heaviest hollow point bullet that reliably expands to the widest diameter we can achieve, while still penetrating between 12-18 inches in ballistics gel. Wouldn’t you know it. That’s the type of rounds we’re looking at now. Check out this video for rifle and pistol caliber stopping power.
The 9mm Caliber Overview
The 9mm round is one of the most popular rounds for good reason. It’s been in existence for over a hundred years and is used by police departments and militaries around the world. That being said, just because it’s a popular pistol cartridge doesn’t mean it’s the best to win a gun fight.
I wrote an article a few months ago, where I summarized the data for over 1800 gunfights. Summarized in the most general of terms, long guns performed better, and larger handgun calibers tended to perform better as well. Take a look at this graph from the article.
This metric depicts the percentage of shootings where a bad guy was shot, and immediately stopped their actions. We can clearly see that shotguns and rifles are working well, as are 44 magnums. The general trend is that smaller bullets have a lower chance of stopping someone after one shot.
The 9mm round has about a 34% chance of stopping an aggressor with just one shot. We can actually see that the .380 ACP is higher. We should realize there are a couple of things in play here. First and foremost, we would actually expect lower chance probabilities of one shot stops with rounds that are easy to fire quickly.
This is why you’re probably seeing 44 magnum working as well as a long gun. Most people shooting these calibers aren’t hosing a target with 6 rounds at a time. We’ll take a look at some more data further on to clarify if 40 S&W is actually a better caliber than 9mm Luger. Let’s take a look at the best 9mm bullets.
What is the Best 9mm Hollow Point?
All of this information is going to come from Lucky Gunner. They have an excellent database for nearly all popular handgun rounds. I highly recommend you check out their website, as they cover the most important things you need to make a good ammo choice. They follow the FBI testing protocols and provide high speed video of the rounds shot through ballistic gel.
Based on what we know of terminal ballistics, we need to pick the heaviest round we can find in 9mm, that expands the widest. It needs to do all of this while still penetrating 12-18 inches of calibrated ballistics gel. Given these criteria, the best performing round is the Winchester 147 gr Ranger T-Series. Check out the video below for its 5 shot performance.
Defensive 9mm Ranger Ammo For Sale – 147 gr JHP – Winchester Ranger T-Series Ammunition In Stock
This bullet expanded to .74 inches, and all 5 rounds showed the same level of expansion. This ammo appears to be reliable, and it best fits our criteria. The next best choice was the Federal 150gr Micro HST. It didn’t expand quite as much but it is slightly heavier, and the penetration was within range. Now let’s look at some great 9mm handguns.
3 Best 9mm Handguns for Self Defense and Concealed Carry
These guns have all been around for many years and have bullet proof reliability. They can handle even the hottest +P rounds that are commercially available. I’ve done reviews on the Heckler and Koch VP9, and the Sig P365. You can read those for all the data you want. Otherwise you can click on the links above to pick up your pistol.
The 40 Smith and Wesson Caliber Overview
This round was invented after the notorious FBI Miami shootout in 1986. The FBI found that their agents were severely outgunned with their .38 and 9mm firearms. FBI agents, in conjunction with ammo manufacturers, came up with the 40 Smith and Wesson round.
The 40 s&w round has higher pressures than the 9mm, and it generates around the same muzzle velocity than normal 9mm loads. You can find lighter 9mm rounds that have a 100 or 200 ft/per second advantage over most 40 caliber rounds, but that doesn’t really mean that it offers superior ballistics.
This round was developed over 30 years ago, and I would argue that in the 90’s the 40 caliber round was probably superior to the 9mm rounds available at the time. That has changed. If you compare the data between the best 9mm hollow point, and the best 40 S&W hollow point, you’ll see that there are pretty marginal terminal performance differences.
What is the Best 40 S&W Hollow Point?
We’re going to be using the same exact criteria that we used to judge the 9mm rounds. We want the correct penetration in ballistic gel, the most expansion, and reliable performance. Here is the best performing round that Lucky Gunner tested, the 180gr JHP Remington Golden Saber.
40 Cal Ammo For Sale – 180 gr JHP Remington Golden Saber 40 cal Ammunition In Stock
All five shots reliably expanded to an average diameter of .82 inches. They did penetrate within the parameters, even if it was on the shorter end of the scale. You can see that due to the higher pressure rounds, you do get a little larger temporary cavity. This may or may not be an important factor, as you’ll see.
The next best performer was the, 40 S&W – 180 gr BJHP – Remington Ultimate Defense. It expanded to .79 inches and had an average penetration of 15.9 inches. Now we can take a look at some great 40 s&w pistols.
3 Best Handguns in 40 S&W for Concealed Carry and Home Defense
There are less choices for pistols in 40. Any of these pistols would be a good choice though. I’ve included a full sized, and compact Glock. I’ve also included the Smith and Wesson MP 40. All these firearms will get the job done, but you should keep in mind the 9mm versions of these pistols have higher magazine capacity.
Which is the Best Caliber for Home Defense: 9mm vs 40?
This is a little more complicated question than it might initially seem. First, home defense implies that you have the firearm handy at home, and that you have no need to conceal the weapon. This matters a lot. Having shot many tens of thousands of rounds of both 40 S&W and 9mm, I can tell you that there are some practical issues we need to consider.
Forty caliber rounds have more recoil. There’s no way around this. If you have a strong enough grip to control the recoil, and are willing to practice so you don’t develop a flinch, then I would say that 40 S&W might be a better round for you. I would recommend you choose a full sized pistol, with as much weight as you can manage. The weight will help tame the recoil.
If you don’t feel confident handling the recoil of the 40, then I would recommend going with 9mm. It’s just a fact, 9mm has less recoil. There are also more pistols to choose from, and the terminal ballistics are functionally the same. More importantly, you will be able to carry more rounds of 9mm than you can in 40. Magazine capacity does matter!
Which is the Best Caliber for Concealed Carry: 9mm vs 40?
The tables turn when we consider concealed carry. The absolute worst firearm to carry concealed is a large heavy pistol. Even if you’re a big guy, who can conceal a full sized pistol, it won’t be as comfortable as a compact pistol. In this case, I tend to recommend a lighter polymer gun like a Glock 19.
These guns are chambered in 9mm, and they are a reasonable size to conceal. If they’re too big you can choose a smaller gun still like the Sig P365, or a Glock 43. Sure you can get a Glock 23, which is the same size as the 19, but you have much more recoil to deal with, and much less magazine capacity.
We know from my previous article, where I analyzed self defense shootings, that it’s very common to deal with multiple attackers, and you will need to carry at least 8 rounds as a reasonable minimum. Don’t believe me, then read the article!
Do Heavier Bullets Stop Bad Guys Better: 9mm vs 40?
As I’ve alluded to above, the answer is generally yes, but there are huge caveats. Let’s go back to my article where I summarized the data from 1800 shootings. We need to check out this very important metric.
This metric compares the percentage of shootings where the bad guy wasn’t stopped, no matter how much they were shot. Again, we see the general trend of smaller calibers performing poorly. Even with a 12 gauge shotgun, there’s still a 12% chance that the assailant won’t stop when hit.
If we consider 9mm vs 40, there is almost the exact same chance that the bad won’t stop their aggressive action. This is important to consider. To me this highlights that the probability of incapacitating someone is roughly the same when comparing 9mm vs 40. Sure, some of the data might give a slight edge to the 40, but I like to keep this in mind. If you’ve been punched by Mike Tyson, or Connor Mcgregor, does it really matter? You’re still knocked out!
Human Factors: What Actually Stops Bad Guys?
We’ve covered a lot of data on terminal ballistics relating to 9mm vs 40 caliber rounds, but we’ve neglected some crucial practical considerations for self defense. There are only two ways to stop a bad guy, when using a firearm for self defense: a psychological stop, or a mechanical stop.
A mechanical stop is striking them somewhere in their body that makes it physically impossible to continue their violent actions. This generally means somewhere in their central nervous system, but it can mean their hip box as well. When these structures are hit, the bad guy can no longer do bad guy stuff, no matter what drugs they’re on, or how crazy they are. As we know, head shots require extremely accurate hits that you general won’t be able to produce in a gunfight.
This leads us to the most common method, the psychological stop. This is simply inducing the fear of death or serious injury in the assailant by shooting them. No one likes to get shot, and the vast majority of people will cease their aggressive actions when shot, no matter the caliber. In the majority of cases, they are still physically able to fight, however, they psychologically do not wish too.
It’s important to realize that wether a bad guy dies or not is irrelevant. This might be controversial, but we don’t actually need to create lethal wounds. Our goal is to stop their actions, not kill them. This is why blood loss really isn’t a factor when talking about self-defense situations. A larger caliber will disrupt more tissue, leading to faster blood loss, but that’s minutes if not hours down the round. It doesn’t help us right now. So where does this leave us?
Final Thoughts: 9mm Vs 40
Given the data that we’ve reviewed I think the 40 caliber has a slightly better chance of stopping a bad guy than 9mm, on paper. If we consider that the vast majority of bad guys are stopped simply by being shot at, then I think that small theoretical advantage disappears.
There are more 9mm handguns to choose from, and they have higher capacity. They are more comfortable to shoot, and you can purchase ammo at a cheaper price. All of these are practical advantages that can’t be ignored.
I can tell you from personal experience that I’ve carried both calibers for many years and probably shot in excess of 100,000 rounds between the two of them. I prefer the 9mm, and I don’t feel under gunned no matter what. I would also point out that units like Delta Force, and DEVGRU (SEAL Team Six) also regularly carry 9mm handguns, and they can carry whatever caliber they want. They also regularly get into actual gunfights!
At the end of the day you should make the decision for what seems best to you. Both calibers work well, provided that you put in the work to build real skill with a pistol. If you have any comments or questions put them in the comments section below. Now get out there and get training.
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This article is well thought out and researched as all Tier Three tactical articles seem to be. You make excellent and valid points on the 9 vs 40 discussion. It may be simplistic to state the best 40 is just barely better in ballistic tests than the best 9mm and the added recoil with less capacity make the 9mm the better choice for most people in most circumstances but that wouldn’t be an article and people would surely argue the minute details of one caliber or the other. I liked that you included the very real factor of psychological stops as it often goes unmentioned or only cursory covered. Since the vast majority of violent criminals flee or stop without physiological impact of a bullet I think this gets too little coverage compared to caliber, bullet design etc.
The bigger issue concerning wound ballistics in handguns that seems to be missed is the changes over time that the FBI testing process and evaluation is lacking for common concealed carrier and even LEO considerations. The FBI tests don’t penalize loads that penetrate too deeply. No points are subtracted by bullets that penetrate 20+ inches whereas any bullet that fails to penetrate 12″ is heavily penalized. FMJ penetrating 24-28″ would score better than a good hollowpoint of the same caliber that consistently penetrates 11.75″ through all intermediate barriers. Along similar lines the FBI test and evaluation process also grades full weight retention too critically. What does it matter to a threat if a projectile retains 100% weight or 75% weight if the penetration, expansion, and wound cavity is the same? It gets worse when a projectile can fragment and fragments leave the main bullet path to cause secondary wound channels. The FBI scoring penalizes this rather than rewards it. Then there is the modern ammunition changes that allow loadings to reach much higher velocities where temporary stretch cavity MAY be a legitimate wounding factor. Some loadings are reaching 2100FPS in 357 SIg, 2000+ FPS in 9mm and 40 and when considering FN5.7 or similar less common caliber even higher velocities.
The FBI focusing so heavily on wound ballistics was seen in the early switch to 10mm and the 1076 which was big, heavy and not easily carried or shot by agents of all sizes and statures. Then the switch to 40 S&W which was good enough for years of service but still offered less capacity, more recoil and challenges to qualify and more wear and tear on guns. Now they (and a fast growing LEO community) are back to 9mm. If the FBI would have considered the factors of shootability, qualification, shot placement ease and importance as much as or more so than wound ballistics things may have progressed differently. All things equal a lighter bullet recoils less than a heavier one. a 115 9mm at 1000FPS has less recoil than a 147 gr 9mm at 1000FPS. Getting the wounding capability is important but getting the shot placement and qualification out of all agents(officers, deputies, citizens ) is more important but not focused on with the same fervor.
Lastly modern bullet design of solid copper hollowpoints, screwdriver style points like Lehigh Defense or similar designs and materials not available when FBI testing protocols were established may offer benefits not considered or not properly developed by ammunition makers because there is no push for such advancements from the FBI and the Law Enforcement community that eagerly follows the FBI trend setting. I had hoped there would be more development of the cutting principal as seen in the Black Talon/Ranger series projectiles as the wounding capability seen in archery hunting with cutting edges at much lower velocities and energy or momentum levels is clear. However that type of wounding and bullets was never encouraged or developed. I’ve rambled excessively so I’ll stop now but I always appreciate the quality writing I find at Tier Three Tactical and hope to see more in 2022
A very insightful comment. Thank you for taking the time to give us your thoughts. I agree on almost all points, and I do think the shoot ability is the main benefit of the 9mm for police agencies as a whole. Interestingly enough after watching a few random 45 acp videos on Lucky Gunner, a few of those bullets actually displayed significant stretch cavities, so much so that I think it might need a future article written on the subject. Happy new years!
I Carry all Calibers and Shoot Enough(Practice) with all that l Carry also. I even Carry a North Amer. Arms 5shot Revolver/ Derrininger in 2in. But in 50gr..22mag. at 2000fps. Quite effective at 5-8ft.
It may well be effective, but there’s no .22 mag that hits 2,000 fps out of a 2 in. barrel. Most likely well less than 1,000. Still better than nothing, and still good.
There are a lot of little things off in the article that probably should be addressed. The whole wear and tear on the guns- initially manufacturers Just took 9 mm and stuff them with 40 caliber barrels and such which cause some problems in some guns. As the caliber became more popular that was rectified by actually producing handguns designed for 40 caliber. Also, it is not a high pressure round. In addition, overwhelmingly winners and losers are determined Within the first 1.5 shots. More shots just being shot because of the high stress situation or people shooting blindly. And though it is true that just brandishing a firearm will stop some 90% of aggressors. Out of the 10% that are left, there is a small percentage that will not stop after being shot at or hit. Your bullet must be placed in a location that will stop them. The best badass 9 mm bullet is a good bullet but it’s still not a 40 caliber bullet. What is your scenario for a gunfight that you might be in? Is it you against four or five bad guys and shooting all these rounds? Perhaps it’s more like one or two people trying to get your wallet or purse or invade your house…. 1.5 rounds determines the winner… So five rounds and a 38 special is better to have with you than the 9mm with 17 rounds you left at your house. Training is great!! Takes time takes money and reality is in high stress situations even the so-called professionals screw up. Again, what is your criteria of attack? A Mugger is a good scenario. They will be within a few feet of you. Pull out your pistol, if it has a safety take it off point at the person, pull the trigger…. If it does not fire are you going to have time to and remember how to fix the problem? 38 stub nose or 9 mm stub nose revolver you don’t have to just pull the trigger again. There are so many choices out there for personal protection concealed carry situations. If you’re not a person who trains regularly, weekly even. You need to make sure your protection is something that is foolproof like a revolver or if you can find one double strike capable pistol. Remember, the most trained people out there will mess up under pressure. I’m not talking about the person who knows something’s going to happen that is put on their vest that has their gun ready and is going into the fight. I’m talking about that person that out of nowhere all of a sudden realizes they need to do something. My two cents
Like you said, it’s an individual choice. I bought my 40 S&W (Kimber 1911) when 9mm really weren’t too common. I’ve carried it for a bit over 20 years. For me, it’s the perfect CCW. For my wife and daughter it would be horrible, it’s too “snappy” my wife prefers a 38 revolver, and my daughter loves her 9mm. The important thing for all 3 of us is we’re all extremely accurate with our chosen CCW. Something as stressful as an actual gunfight will really reduce that accuracy, so regular practice is important.
Very well said Grant
I carry a Sprfld.XD-Hi-Cap. .45Auto(15rd.mags) my main Carry gun with 175gr. Hydro-Shoks at 1250fps. Very Effective. 96% one shot Stops(kill). Also carry 9’s,40’s,38’s, even 10mm’s all very good. And Deadly Guns.
It is rather obvious that this article (like many others) is written by a fan boy.
A fan boy of what?
9 mm
Yep
To anyone out here that thinks 1990’s 9mm ammo was all weak and anemic compared to what is produced today- ever heard of (or better yet actually been to the range with and felt the power of that stuffs recoil impulse in real life- it’s HOT but still controllable, some great ammo) Corbon +p+ or federal +p+??
Yes, l use to live in Sturgis, So.Dak.& worked at the Corbon Factory loading their Ammo. Awesome Stuff forsure. What a Great Job that was. I had Truely learned to Load Ammo by Factory specs.
I prefer a 40cal over the 9mm simply because of the power of the 40cal. Yes if the handgun is to large for your hand then get a smaller gun. I got rid of my Sig P229 in a 40 for a Sig P320 40cal compact, excellent choice problem solved.
I have an SW.40 and its hard to pull back and too big to carry
Overall not a bad article by any means. Well written and advances certain lines of thought convincingly.
I will point out that while the “ABC” military units thar are allowed the pick and choose whatever pistol caluber they would like, and allegedly with 9mm being the caliber of choice, that “choice” as it is may include a point of logistics.
Logistics in that one will find 9mm much more available than 40SW in areas in which the “ABC” units are deployed.
As to “this calibers is better than that caliber” really comes down to what caliber (or pistol or revolver) are YOU comfortable with to carry and hit your intended target.
That is the “litmus test”, that is what defines YOUR confidence.
What caliber that whoever else carries us of no consequence. If YOU have no confidence in your choice or ability to consistently hit your intended target, then there is no solution.
I believe it boils down to the following: the .40 is better; the 9mm is close; there’s no difference in recoil to a first order estimate, and recoil is far more gun-dependent than caliber-dependent. Is it 20% better than 9mm? Yes. I say that because I choose my 10+1 .40 over my 12+1 9mm – pistols otherwise ~”identical.”
Why ~? Because the 40 recoils LESS than the 9mm in these two guns – Taurus G2 concealed carry guns. I first noticed when comparing them side by side at the range. I asked, over several weeks, 3 other people to compare them double blind. All 3 concurred, and insisted the 9mm was the .40, expecting the .40 to have higher recoil impulse. These are identical in weight, shape, you name it. YMMV.
It may be that law enforcement moved back to 9mm because of a poor gun choice, rather than caliber. I have a Smith 4006. It was a popular LEO gun. It weighs a POUND more than the Taurus. Its recoil is FAR greater. It’s about ergonomics and barrel axis height – in fact, I bought the 4006 from a guy who didn’t like the “recoil of a .40” and was going back to 9mm. This was before I had the Taurus G2s.
Also, there’s no improvement in 9mm bullet technology that has not also become available in .40. The only reason to choose 9mm is if you value the higher magazine capacity; for me, the .40 is just a bigger, deeper hole, and that’s what spare mags are for, so .40 is better.
Ammo price can admittedly be a consideration, but not when my life is at stake; my defense load is the ammunition equivalent of Wagyu steak. And it’s FAR better to use a MantisX than to waste powder, lead, and money just for gun familiarity and trigger control/muscle memory. No cleaning, no barrel wear, far better results.