9 vs 45, a different look at it

I agree with what you are saying, I just put more stock in speed. There’s high tech and there’s low tech. Increasing speed is the low tech way to make things expand. With everything else being a variable, (speed is too, I know) speed is more of a constant.

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About 6 years ago they had some, but after that they went to 230 grains

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I am with you on speed being a factor for “guaranteed” expansion. Ballistic analysis for our 9’s show the importance of a 4" barrel over the sub length versions for EDC. It was a contributing factor for I why I switched from a Glock 43 to a Gen5 19. The design of the 9 mm shows a markedly large difference between a 3" and a 4" barrel. The gain by going from a 4" to a 5" is very little by contrast. Ballistics are just that.


Here are two of my carries:

Here is the ammo for each:

9mm = 115 gr x 18
.45 = 230 gr x 9

Seems like a wash. Just boils down to aesthetics and comfort.


Speed is just a portion of the equation. For bullets that are designed to expand (as opposed to tumbling or fragmenting) they usually have a “window” of speed in which they will expand reliably and achieve an appropriate level of penetration.

What is sometimes counter-intuitive is that if a bullet is going “too fast” it will expand too early and actually decrease penetration. That is because the expansion acts like a parachute, with more drag on the medium its going through. The reason that is bad is it might not have sufficient penetration to reach any vital organs.

If the bullet is going “too slow” then it might not achieve enough resistance to expand at all and then it will act like an FMJ and actually over penetrate. The reason that is bad (beyond maybe going through your target and into something you didnt mean to hit) is that you arent dumping all the energy into the target if it ice-picks all the way through.

This was really more prevalent with older hollow points where most of the testing was done with duty-size pistols with barrels of 4" or 5" (think LEO usage). The rise in popularity over the last few decades of Concealed Carry, and Pistol Caliber Carbines has thrown that older technology on it’s head. The really short barrels of a typical CCW pistol have challenged the low-end velocity thresholds of these rounds, and the really long barrels of PCCs have challenged the high-end velocity thresholds. I think most of the current generation hollow points from reputable manufacturers have a pretty generous window, but its worth researching any particular round in the firearm you plan to use it in.


The 75% may be skewed by the large number of departments that issue firearms and do not allow individual LEO’s to choose their weapon. In NYC alone with over 50,000 total LEO’s they have a choice between 3-9 mm’s. two Glocks or a sig. Feds left the 9mm for the 40 and they have no choice on what they carry. Most counties allow LEO’s discretion.

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@KED The reason for the preponderance of LE/MIL purchasing 9mm is that the ammo is cheaper. In the lifecycle of a firearm, you spend more money on ammo than the firearm. It is cheaper to train/maintain with cheap ammo.

Back in “the day” it was 9mm ball vs .45 ball. In that situation the .45 is tough to beat. Modern ammo helps significantly to level the field. But all warm .45 is still a bit stronger than equally warm 9. Both beat the pants off the old .38 Special the cops carried for decades, both are pretty weak sisters compared to .357 Mag or .41 Mag. You pays your money and take what works for You. My EDC and HD are both currently 9mm. I’ve shot and carried .45 and .357. Frankly it hit faster on follow up with the 9’s… if I’m in the toolies where nasty critters live, or deer hunting, I don’t mess with any the above, instead I carry my .44 Super Blackhawk. The “best” is what. Works for You and is able to deal with what you expect to shoot.

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That is obvious. My post was in response to the idea that 75% of LEO’s choose 9mm. Most do not have a choice, their Dept. decides for them.

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I couldn’t resist…

Ideally a good hollow point will dump all of it’s energy into the target. As a ballpark figure, 9mm will be somewhere in the ballpark of 350ft/lbs of energy. .45ACP will be somewhere in the ballpark of 450ft/lbs of energy. A difference of 100ft/lbs may sound like a lot… but thats less than the muzzle energy of a .22LR (~150ft/lbs of energy).

Its not until you get up into the arena of very hot 10mm or 44 magnums where you might see a significant increase as you creep into the 700s of ft/lbs of energy (which would be roughly double a 9mm).

So if you accept that .45ACP is “better” ballistically than 9mm, but not a “way better” then other things come into consideration.

Weight of the firearms. An all steel 1911 is heavy, and manages to tame the recoil of a .45 very nicely. But it’s heavy in comparison to a polymer 9mm with similar recoil. If you lighten a .45 firearm to roughly equal a polymer 9mm in weight (lets say with a Glock in .45ACP) your felt recoil increases. This affects less experienced shooters (think rookie LEO too) as well as anyone who may have hand grip strength issues making it harder to control for follow-up shots.

Weight of the ammo. A full mag of 15rnds of 230gr .45ACP compared to 15 rnds of 115gr 9mm is not even close.

Cost of ammo. The cost of .45ACP isnt that far off from 9mm. Most places online (not counting shipping) are around $0.25-$0.30 per round for .45ACP and $0.18-$0.22 per round for 9mm. For occasional use by citizens that’s not much. For an agency purchasing by the truckload… thats a lot of money.

Some food for thought by guys who know .45 & 9mm

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Got it. I’m not toting for Mil/LE anymore and choose a .45. My “comfort” caliber for conceal carry. I have a 80 year old neighbor that is still hitting steel plates at 100 yds. with his. The difference between driving an F150 and a Fiat :laughing:


I carry an XDs in .45. I have a S&W M&P shield in 9mm, buy prefer the springfield. It’s just as comfortable to carry and easy to conceal. I feel more confident with a 45.


When I was a kid the .45 was the go to caliber. At Parr is Island we got to shoot 1911’s one day, I believe one mag. All but one guy could hit anything.
I now own both calibers in striker fired guns. I believe both, with the new ammo, are very deadly. I prefer the 9mm. Bigger mags favor the 9mm and I love the federal and hornady defence ammo.

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I think it is too easy to overthink this. Both cartridges have failed and both cartridges have been one shot wonders, but before you can attribute anything to either, you’ve got to hit your target.

I think time is better spent on the range hitting targets than debating pros and cons.
Not that there aren’t pros and cons to debate.

In jurisdictions were magazine capacity is restricted to 10, perhaps that gives a nod to the .45. With an 8 round magazine, Nine (8+1) .45 doesn’t seem too great a handicap over Eleven (10+1) Parabellums.

There is also a confidence factor—if you’re more confident with a CZ-75, you’ll likely shoot it more accurately than a Colt 1911.
As impressionable as new shooters are, running down one caliber while extolling the virtues of the other tends to question if not destroy a shooter’s confidence in their selected “tools.”
Sure you can trade handguns, but learning any new handgun takes time.
For most of us it’s struggle just to find the time to train with the firearm we already have.

Either round can do the job if deployed by an aware and accurate shooter.


@John292 Good point. I hope everyone understands we are ribbing each other… I got to watch some of the history unfold here in the USA on .38 to 10mm to .40 SW then 9mm transitions. Most of it played out after the Miami-Dade County Shootout in 1986.

I would rather members of our community find a comfortable firearm and train well with it. A mental and physical activity. Being able to handle a firearm safely, confidently and understand when to use it. There are no do-overs in real life.

Many or most of us here are more than EDC people we are enthusiasts. As such we may have been through the transition from .38 specials to 357, .45 and 9mm. Many of the same advancements that have made the 9mm better also make the .45 better and expanding ammo is one. For home defense I might prefer a .45 with 185 grain Golden Saber +P or Speer Gold dot. I like Speer gold dot for a 9mm as well. But the 9mm doesn’t carry that many rounds either because I can’t stand for a weapon to print. So I like single stack thin weapons.

The .45 is not likely over penetrate so at home with neighbors I prefer the large hole it makes to the 9mm. And I have extra mags for each gun. Still if we can afford it some of us carry both or either. In fact when qualifying, if it has been a while since I have been to the range, my .380 is easier to shoot. I have found that a ported .45 is almost as easy to bring back on target as a 9 mm with a 3-3.5 inch barrel.

I think the idea that a .45 that expands to twice its diameter or a 9mm expanding to twice its diameter give you a visual of what to expect from both rounds for defense.

Yes for extended time at the range a 9mm burns through less money. But you can get most of the same guns we carry in a .22 and that is even less cash.

Yes I like the flying ashtray. I Like a 9mm as well. Still there is just something about looking at that just shy of your finger sized round as you loan it into a magazine that makes you feel if you have to hit something with it the round is going to stop the aggression at the terminal end of where it is headed.