9mm is the best caliber for the 1911

springfield 1911 in shaggy aiwb with PMC 9mm

The 1911 is probably the most iconic handgun design ever. No pistol in history has done more – from battlefield to CCW to every single flavor of competition, there are 1911s. It’s just a great gun. It’s also at its finest when it’s chambered in a cartridge it wasn’t originally designed for: 9mm. Now, before you come burn my house down, hear me out because there’s a method to my madness. Yes, I know that it’s harder to make a 9mm 1911 run right than a .45. Yes, I know that the 1911 was originally designed for the .45 ACP cartridge, and that saying it’s better when chambered in 9mm is tantamount to heresy. But it’s heresy like Galileo’s heresy, because I’m actually right.


Let’s look at defensive uses first: we know for a fact that there’s no difference in terminal performance between .45 ACP and 9mm (cue the ballistards), so there’s no point in giving up 2-3 rounds of ammunition capacity, right? If you can carry more, do it. A 1911 with 11 rounds of 9mm on tap has 122% of the firepower of a .45 ACP with 9 rounds in it, and if that kind of made up number doesn’t change your mind, try this: 8 rounds of 185 grain JHP weighs 1480 grains, but 11 rounds of 147 grain 9mm JHP weighs 1617 grains. THAT’S MORE GRAINS! ALL ABOARD THE GRAIN TRAIN!

To bring things back to reality, consider ease of shooting. Everyone regards 1911s as being wonderfully easy to shoot, thanks to what are still some of the finest ergonomics ever found on a handgun. So what happens when you dump that uneccessarily large cartridge that doesn’t offer any performance advantages in favor of a light weight, soft shooting 9mm that works just as well? You get a gun that’s so stupid easy to shoot well it’s almost criminal. Honestly, one of my favorite things about testing all these 9mm 1911s is how easy they are to shoot. They’re heavy, they soak up what little recoil there is; and it’s really just a good old time.

Lastly, consider the following: in every single other platform, 9mm is better. 9mm Glocks? Best Glocks. 9mm sub-guns? Best sub-guns. So why not 1911s? Besides, think about this. When John Moses Browning designed his next pistol, he designed the gun that he would have made if the Army hadn’t insisted on certain design parameters. What was the result? A double stack 9mm pistol. Sure, the Belgians gayed it up with that magazine disconnect, but otherwise it’s perfect. Just like the 1911 in 9mm.

23 thoughts on “9mm is the best caliber for the 1911”

  1. Agreed. Shooting an all steel 1911 in 9mm is cheating. Hmm, maybe that’s why I won my IDPA league tonight.

  2. While I agree with your 9mm conclusion, your total payload math appears to be off. An 8 round .45 mag plus one 185 grain round chambered equals 9 rounds times 185 grains totaling 1,665 grains of ballistic payload—which 1,665 grain total is slightly more total ballistic payload than your quoted 11 round 9mm total payload–but 9mm still wins for all of your other cited reasons—plus lower cost, lighter weight, and greater availability. Thanks again for your constant thoughts, insights, research, and blogs–we all appreciate and learn from them. DMD

  3. Heh, I have a wonderful pair of 1911s, in 45 and 9mm. And the 9mm is the one I tend to grab the most often just for fun times. Never thought I’d see

  4. Every discussion of the 1911’s celestial superiority over every other machine made by man always starts out with: It shoots the super-awesome .45, that will throw the bad guy through the nearest plate-glass window if it hits him in the finger! The 1911 is by definition the best ever because because those plastic toys or DA/SA crunchentickers shoot puny pathetic effeminate Europellets that are only good for executing kneeling peasants!
    Now you go out into the world and preach heresy. Col. Cooper (and is it coincidence that his initials are JC? I think not.), were he still around, would take you out behind the barn for a good switching.
    The fact that you’re right is immaterial.

  5. Agreed. I’ve been shooting 1911s in .45 for a long time and until recently I avoided the 9mm versions because they didn’t have the best reputation for reliability–mostly due to poor magazines. However, there are a variety of good 9mm 1911 magazines now and shooting a 9mm 1911 is so easy it’s basically cheating. If you can look past the aura of the ‘mighty’ .45ACP and just look at the facts, there’s no reason 9mm shouldn’t be the primary chambering for most new 1911s made today. That said, the Catholic Church took 350 years to exonerate Galileo, so I wouldn’t hold my breath. ๐Ÿ™‚

  6. I thought JMB (PBUH) said he always thought the Government Model was best used in Super 38 Automatic #gunhipster

  7. 1 x [email protected] lbs each = 14,000 grains of ballistic ‘goodness’. Just throw the gun at the target.

  8. It might be worth mentioning that the one feat of wartime military combat pistolcraft that arguably matches or exceeds Sgt. Alvin York’s exploit with his .45ACP M1911, was the 1975 incident during Operation Savannah in Angola, where SADF Lt. Lourens Van Vuuren dispatched 11 Cuban soldiers with his issued Star Model B – essentially, a 9mm 1911…

  9. No arguments here, except that CZ75s have better ergos. Just my opinion, but yes, 1911s in 9mm are great.

  10. “we know for a fact that thereโ€™s no difference in terminal performance between .45 ACP and 9mm (cue the ballistards), so thereโ€™s no point in giving up 2-3 rounds of ammunition capacity, right?”

    DocGKR says in his Service Caliber sticky: “.45 ACP makes the most sense in states with idiotic 10 rd magazine restrictions…” Doesn’t his statement imply at least a marginal shot-for-shot increase in terminal performance?

    1. I like the rationale that Dave Spaulding(retired cop, gunwriter and defensive firearms trainer) explains in these two videos:


      Long story short, he researched a bunch of police shootings as part of writing and defending his Master’s thesis for a post-graduate CJA degree, and he found that when comparing the wound ballistics between similar JHP loadings across different service pistol calibers, a .45 JHP would cause about 15-20% more damage per shot than a comparable 9mm JHP in controlled ballistic gelatin testing. However, the extra amount of damage is so small, considering the relatively small volumes of the permanent crush cavities that handgun bullets cause in service pistol calibers, that the “on-paper” advantage of .45ACP becomes academic in real-world shootings.

      My personal take is: While one 9mm JHP might only do 80% of the damage of one .45 JHP, two 9mm JHPs will do 160% of the damage of that one .45 JHP. If I’m well-trained and practice regularly and often, it will only take me .15-.25 seconds to fire that second shot on my target with a good 9mm service pistol. If I have to fire several shots to incapacitate an attacker, it only takes five 9mm JHPs to equal the damage of four .45 JHPs. And, while a single-stack 1911 holds enough .45ACP ammo for two 4-shot bursts, my Glock 19 holds enough 9mm ammo for three 5-shot bursts.

    2. I also appreciate the extensive research and analysis that another Ohio cop and firearms trainer, Greg Ellifritz, did for this study:


      If you pay close attention to his findings summary towards the end, Greg notes that on average, it takes 2.45 hits with a 9mm to incapacitate an assailant, versus 2.08 hits with a .45ACP. Again, the .45 has an advantage “on paper,” but since you can’t fire 8/100ths or 45/100ths of a bullet in the real world, you still have to expect to get at least 2-3 hits on target with either caliber to incapacitate an assailant. And, since my 1911 only gives me four 2-shot bursts per magazine, while my Glock 19 gives me five 3-shot bursts per magazine, guess which one I prefer to carry…

      1. The question though isn’t 8 shots of .45ACP vs 15 shots of 9mm, and in my case I’m not even talking about 8 shots of .45ACP vs 11 shots of 9mm — I’m wondering about 11 shots of .45ACP vs 11 shots of 9mm.

        Elsewhere in the Service Caliber sticky, DocGKR says “Unless your department picks your caliber for you, pick the platform you shoot best, then decide on caliber from there. Basically all the standard service calibers work when using good quality ammunition; the platform picked tends to dictate the caliber.”

        But then in the portion I quoted above, he recommends .45ACP for those with limited mag capacity… what this says to me is that for those living in mag-restricted states, he thinks that the slower split times might be worth it for some people, so they can get the increased permenant cavity on a per-shot basis, since the tradeoff of increased capacity for 9mm pistols is not present.

        It’s not that I have a lack of confidence in my 9mm pistol, I’m just wondering if, in the long term, a switch to .45ACP might give a (small) advantage.

        1. Sure, that small “on-paper” advantage is still there, but a .45 pistol designed for a 10+1 capacity will always weigh more and have larger grip dimensions than a 9mm pistol designed for 10+1. I wouldn’t mind owning or carrying a Glock 30S, since it’s awfully close to the size and weight of my Glock 19, but if I lived in a mag-restricted jurisdiction, I suspect I’d be more likely to carry my Glock 26 instead of either the 30S or the 19 with a restricted-capacity magazine – because per-shot ballistics IMO doesn’t quite outweigh concealability, shootability and hand fit…

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