.450 SMC - 10mm power out of a .45 ACP pistol with no modifications necessary?!

Lately I've been doing a lot of research on both the .40 S&W and .45 ACP cartridges because I'm preemptively looking into a large caliber handgun for Winter Carry, plus there have been some rather alarming reports of Black Bear sightings in my area lately.
Initially my findings were that as far as standard pressure loads go, .40 S&W and .45 ACP are so close in terms of energy foot-pounds that it seemed to make more sense to go with a .40 S&W for the higher magazine capacity (15 rounds vs 10) between the Smith & Wesson M&P40 and M&P45. Sure, .45 ACP +P rounds offer a bit more over .40 S&W, but not enough to make up for 5 less rounds in the magazine.

However, something has come to my attention which has left me baffled to say the least, and that's the .450 SMC cartridge. Based on what I've read, .450 SMC is practically a magnum loaded .45 ACP, but unlike the .45 Super, .450 SMC can reportedly be fired from an ordinary .45 ACP +P rated pistol without any modifications necessary.
EDIT: I have been informed that Double Tap recommends a heavier recoil spring specifically intended for firing high pressure rounds. Still, that's a relatively minor modification compared to the ramped barrel with fully supported chamber and recoil buffers that the .45 Super or .460 Rowland calls for.

Yes, according to Double Tap, (the current exclusive manufacturer of the cartridge) .450 SMC can be safely fired from any full-size, +P rated .45 ACP pistol without the need for any major modifications, which they claim is possible due to the fact that the .450 SMC brass is formed from cut-down .308 cases with significantly thicker case walls and a stronger case head.
Obviously, a cartridge which rivals 10mm Auto in terms of energy foot-pounds which can be safely fired out of any full-size +P rated .45 ACP sounds incredible, thus leaving me sceptical of the validity of such claims, regardless of how many articles say that it's true, it just sounds too good to be true. I mean, if it's true, then how am I only just hearing about it now when it supposedly has been in production by a major ammunition manufacturer since 2014? Surely if reports were true then more folks would be singing it's praises, especially in your average Bear Defense thread, right?

So what's the real story behind this cartridge? Does anybody here have any experience shooting .450 SMC who can attest to the validity of the statements made by Double Tap as well as numerous writers? And if it's all true, then how isn't the cartridge more popular/widely used?

I read a couple of articles on it after I saw your post. Sounds intriguing, but even with a stouter spring that kind of energy has to have an adverse effect on anything but a full size GI steel frame. Kind of like the .460 Rowland without changing parts. Cool idea though.

Dirty Harry Callahan said:

Lately I've been doing a lot of research on both the .40 S&W and .45 ACP cartridges because I'm preemptively looking into a large caliber handgun for Winter Carry, plus there have been some rather alarming reports of Black Bear sightings in my area lately.
Initially my findings were that as far as standard pressure loads go, .40 S&W and .45 ACP are so close in terms of energy foot-pounds that it seemed to make more sense to go with a .40 S&W for the higher magazine capacity (15 rounds vs 10) between the Smith & Wesson M&P40 and M&P45. Sure, .45 ACP +P rounds offer a bit more over .40 S&W, but not enough to make up for 5 less rounds in the magazine.

However, something has come to my attention which has left me baffled to say the least, and that's the .450 SMC cartridge. Based on what I've read, .450 SMC is practically a magnum loaded .45 ACP, but unlike the .45 Super, .450 SMC can reportedly be fired from an ordinary .45 ACP +P rated pistol without any modifications necessary.

Yes, according to Double Tap, (the current exclusive manufacturer of the cartridge) .450 SMC can be safely fired from any full-size, +P rated .45 ACP pistol without the need for any modifications whatsoever, which they claim is possible due to the fact that the .450 SMC brass is formed from cut-down .308 cases with significantly thicker case walls and a stronger case head.
Obviously, a cartridge which rivals 10mm Auto in terms of energy foot-pounds which can be safely fired out of any full-size +P rated .45 ACP sounds incredible, thus leaving me sceptical of the validity of such claims, regardless of how many articles say that it's true, it just sounds too good to be true. I mean, if it's true, then how am I only just hearing about it now when it supposedly has been in production by a major ammunition manufacturer since 2014? Surely if reports were true then more folks would be singing it's praises, especially in your average Bear Defense thread, right?

So what's the real story behind this cartridge? Does anybody here have any experience shooting .450 SMC who can attest to the validity of the statements made by Double Tap as well as numerous writers? And if it's all true, then how isn't the cartridge more popular/widely used?

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Double Tap is a reputable company so I have no doubt there is some validity to the claim.

With that said, I've never heard of this rounds nor seen any information on it.

Going completely off your post and what I know about ballistics in other calibers Id say its never taken off because there isn't a need for it. Most people carry a caliber for self defense that they can easily conceal....a full size +P rated 45ACP gun usually isn't the conceal carry pick for most people.

Second, firing any +P round in any firearm.....consistently will wear it out quicker/need replacement springs quicker and with the availability of standard rounds with good designs, good powders there isn't a large need to produce/constantly fire +P ammo.

Of course firing a couple hundred rounds likely wont hurt the firearm but feeding a +P rated 45ACP firearm with that 450 SMC 1,2,3K rounds or more will likely beat the gun up a bit.

Now, if you are seriously concerned about bears and that is something you believe you are likely to encounter day to day.....and feel you have to have such a round Id 100% agree and tell you carry it.

That said, 40S&W/45ACP will work just as well, in my opinion with much less wear on the gun, less need for parts changing after high round count and most important to me.....ease of access to the round.

As you said its not a super popular round....so it likely wont be around a long time unless it catches on......and if it does catch on...with only 1 company making it....it may get hard to obtain.

All that taken into consideration.....If you want the 450.....go for it, try it out....Cant hurt to buy a box or 2.

The 450SMC is the 45 SUPER

I am a big fan of this concept, but safety first

45 SUPER is a registered trade mark and to use that name the company that owns the trademark insists on being paid a royalty

To get around the trademark issue, a new name was created and new brass was formed. They used a small primer instead of the 45 SUPER's large primer and BINGO you have a different product . . . 450SMC

Both cartridges are loaded to the same performance levels. Both cartridges are children of the 451 Detonics Magnum case. The 451 Detonics Magnum case is formed by cutting 7.62x51 brass to the correct length

You ABSOLUTELY must change the recoil spring if you intend to shoot 450SMC in your auto loading hand gun with the exception of the full size HK USPs

Not doing so will not cause a catastrophic failure, but it well cause excessive battering of the frame. Due to this issue I would avoid alloy framed auto loaders unless longevity is not a concern

I know of no where on Double Tap's site where it says to use a original recoil spring. In fact Double Tap's site specifically states that your firearm should be changed to a at least a spring designed for +P use. Some folks are mistakenly interpreting the Double Tap cautions to mean that if their handgun can shoot +P it is 450SMC ready

Using a barrel that does not have a fully supported chamber will not cause a catastrophic failure, but it can lead to bulged brass which is a hassle for hand loading


I only own one firearm that was specifically designed for the 45 SUPER, but I have fired tens of thousands of rounds of it through various HK USPs and Smith and Wesson 625s since I first started using the cartridge back in the 1990s.

Ehhhhh... personally, I do not think dropping in an extra heavy recoil spring is the correct solution. It's the easy solution, but that extra energy recoil spring is going to slam the slide forward with far more energy than the stock spring. This puts additional pressure on the slide stop pin, pin hole in the receiver, and whatever bottom locking lug system there is on the barrel.

My experience with a near magnum pistol cartridge has been with the 10mm in the 1911. The best set up for the 10mm, and I would put the 45 Super and .450 SMC in the same class, would be a bushingless, cone barrel, preferable with an integral feed ramp. The heavy cone barrel adds mass and helps to delay the unlocking of the pistol. An 18 pound recoil spring and a shock buffer, a 25 pound main spring, and a flat bottom firing pin stop with just a tiny radius on its leading edge. This will all resist the increased energy of the 10mm, 45 Super, .450 SMC without battering anything.

I'm skeptical. .45 ACP is about a 21,000 psi load. The chamber walls of a 1911 in .45 are much thinner than one in 9mm, .38 super, or 10mm. I don't believe a recoil spring will fix that. Maybe playing with fire here.

Here's an original kit.It even has loading data in the book.Brass was available for $12.50 for a box of 50.No date listed on manual.Sorry about the upside down picture.

Univibe said:

I'm skeptical. .45 ACP is about a 21,000 psi load. The chamber walls of a 1911 in .45 are much thinner than one in 9mm, .38 super, or 10mm. I don't believe a recoil spring will fix that. Maybe playing with fire here.

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Standard pressure .45 auto is plenty for me, but a 1911 barrel can probably take it, if a 625 cylinder is a fair comparison. It can be rechambered for .460 Roland, and the chamber walls are much thinner than a 1911 barrel.

.45ACP brass shares the same case head and rim dimensions as the .30-06 class (which also includes .308, .270, .243, etc). Making the brass should require no more than cutting to length and perhaps some inside neck reaming. Such brass would likely have much greater strength at the base head and web due to the thicker cartridge case walls.

However, the thicker brass would necessarily result in reduced interior space, so chamber pressures would be expected to increase even when standard powder charges were loaded. Increasing the charges to the so-called +P level would, in my opinion, be something best left to experienced folks with access to a fully equipped ballistics laboratory. I suspect that any significant performance gains would come with large increases in operating pressures.

An interesting subject, and probably an interesting exercise for those sharing the interest. Certainly nothing for the novice or beginner to play with. Also something that would completely void any warranties that might otherwise apply.

"Hey y'all! Watch this!"

Why bother? Just carry a 10mm instead.

.450SMC = .45 "Same Mother-loving Cartridge" as the .45Super.

I was going to convert my SW1911 all steel 5" bbl to .45Super / SMC, but my son has swiped it for IDPA and I won't muck with it until he is done with it.

Snooping around, it seems the first (and maybe only) thing to do is switch out the firing pin stop for a shiny new one with less generous radius/chamfer, thus keeping the bbl & slide from moving after firing for a smidge longer. Supposedly this allows chamber pressures to be reduced when it finally does move rearward and recoil velocity of the slide is reduced to usual 1911 levels.

Some folks' idea of "less generous" is to leave the FPS a 90deg affair.

This does make the 1911 slide harder to rack.

marshall tom wrote:

Why bother? Just carry a 10mm instead.

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If you already own a .45ACP GM, .45Super/SMC is only a FPS away.

Comparing the 10 mm, 450 SMC and .45 Super - Marksmanship Matters | Comparing the 10 mm, 450 SMC and .45 Super for Predator Defense

Just so you know...the recoil energy of the slide/barrel of a .45 Super is about 22 jules in a full sized auto...it is about 11 joules in a standeard .45 acp. The recoil spring can absorb less than 2 joules so you can see that changing the recoil spring does little to prevent the gun from being battered...Slide/barrel mass is the most important thing. You CAN shoot .45 Super in any .45 acp that has a ramped barrel but unless it is a full sized gun it will probably suffer damage over time. Do the calculations yourself...starte with conservation of momentum..

kingrj said:

Just so you know...the recoil energy of the slide/barrel of a .45 Super is about 22 jules in a full sized auto...it is about 11 joules in a standeard .45 acp. The recoil spring can absorb less than 2 joules so you can see that changing the recoil spring does little to prevent the gun from being battered...Slide/barrel mass is the most important thing. You CAN shoot .45 Super in any .45 acp that has a ramped barrel but unless it is a full sized gun it will probably suffer damage over time. Do the calculations yourself...starte with conservation of momentum..

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Don't forget you can shoot them in a S&W 625 .45ACP revolver.

Put in a 23 lb recoil spring. Make sure that you have a 23 lb main spring. Make sure that you have a forged frame (not cast or aluminum). Switch out your firing pin stop for one from Harrison Design

Harrison Design & Consulting, LLC. HD-205 Extreme Service firing pin stop for .45 Gov'''t Model, S-70

The bevel on the FPS is important because it delays the unlocking for a tiny fraction of a second. Long enough to get beyond the pressure curve before unlocking I am told.

Anyway, check out the pressure generated by a .450 SMC, then check out the pressure generated by a 10mm, a 9mm, or even a 38 Super. The pressure generated by this round is very similar to the pressure generated by any of these three calibers. It will not do any more damage to the gun than any of these.

I converted a TISAS several years ago. I have shot a bunch of the hottest rounds that DoubleTap sells out of it. Not a sign of any kind of wear yet. Nothing. It is my carry gun.

I would add that everyone has an opinion on this. Most are BS. I would get my info from people who have actually done serious homework and/or have actually done it. Yes, it is going to wear the gun out quicker than a gun that spent its life shooting .45 ACP target loads. Just like the other calibers that I have mentioned will put accelerated wear on a 1911 over typical .45 ACP ammo. They are all similar pressure. But, unless you plan on shooting a thousand rounds a week, you probably will not live long enough to wear the gun out. If you can afford to shoot a thousand rounds of DoubleTap stuff a week, you are not someone who has to worry about the price of a 1911.

Sounds like a job for a Star Megastar.

If you're cool with a 5" 1911, carry a 6" Grizzly in 45 WIN Mag.

Funny that this old thread should be revived, as I've since gained more knowledge along with a bit of personal experience on the subject.

Last year I bought an H&K USP45 Elite, one of the few firearms in current production that can handle .450 SMC without the need of extensive modifications.



As folks have said, .450 SMC is really just a modified, non-proprietary variation of the .45 Super, with the main difference being that it's made from cut down .308 brass with a small rifle primer instead of a large pistol primer.
However, it's important to note that .450 SMC is loaded just a bit hotter than .45 Super, at least when comparing factory loaded Double Tap .450 SMC to Buffalo Bore .45 Super.

Having shot a few rounds of the stuff, (not many, as it's expensive, especially since I can only find the stuff online and shipping isn't free, regardless of how much you order) it's surprisingly soft-shooting (at least out of my USP) yet clearly quite potent. I went digging for some of the bullets once thinking that they couldn't possibly go far into damp earth, yet the holes just kept going and I had to stop digging before I found any.

Granted, those were FMJs, whereas JHPs are a whole other story. It seems like JHPs, especially light for caliber 185gr bullets expand really fast yet don't penetrate for beans.
Fortunately, I've always been of the mindset that heavier bullets are better, so 230gr-255gr bullets are my go-to loads. Besides, I never really planned on making the USP45 Elite my carry gun, not unless I were going hiking in the woods, anyway, in which case FMJ would still be the better choice, so it's a non-issue.

Marshal tom said:

Why bother? Just carry a 10mm instead.

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That was originally the conclusion that I had reached, but 10mm pistols were unobtainable in mid-2021, so I opted for the USP instead, which I found a crazy good deal on too, no regrets.

Besides, there's something to be said about a .45 caliber pistol with similar performance to 10mm Auto. If nothing else, it's an interesting alternative with a bit of a novelty factor.

WHY..........Do people want to turn a Volkswagon into a Dodge Hellcat?....... Knowing the VW is not setup for it......Why not just buy the Hellcat instead?.........Lots of GOOD std 45 acp rounds out there without using Boutique ammo that could stress and batter your gun. Plus all that ($$$ ammo)would never shoot to point of with a fixed sight gun.

First of all, comparing a .45 ACP to a Volkswagen is all kinds of wrong...

Second, it's completely safe to shoot .45 Super/.450 SMC out of a USP, it's kind of a selling point of the gun, that they're overbuilt, and if you've ever held a full-size USP, much less an Expert, Elite, or especially an Mk23, you'd know immediately that they could take it. The things are built like tanks and have a service record to prove it.

Lastly, because modifying things to make them stronger, faster, and better is an incredibly fun as well as rewarding experience, so even those who are modifying old 1911s to run hotter ammo have their reasons.