Guns and Gear

CCW Weekend: Why We Wouldn’t Have 10mm Or .40 S&W If .45 Had Gotten More Attention

The Colt 1911 was a popular gun among many different criminals of the era. It also fired the powerful .45 ACP round. (Credit: Shutterstock)

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By Sam Hoober, Alien Gear Holsters

Ordinarily, this column tries to steer clear of silly gun arguments because they’re usually pointless. This time, we’re taking a detour thanks to a discussion I got into recently with a friend and decided it’s actually worth this trip into the weeds.

Besides, why not distract ourselves with a silly gun argument during these troubled times? Commence to arguing in the comments.

It’s possible that 10mm and .40 S&W wouldn’t exist if enough people had bothered with developing .45 ACP to its full potential instead. Not only that, but it would have avoided most of the problems that 10mm and .40 S&W are associated with.


Ha ha ha ha!

Let’s seriously consider the idea for a moment.

When .45 ACP was developed, the market generally preferred a flying ashtray for personal defense. Slow, heavy bullets that reliably punched through tissue; the notion of a FAST heavy bullet hadn’t really occurred to anyone yet. The .44 Magnum was still 40 years in the future.

The original factory load of .45 ACP was a 200-grain round nose FMJ with muzzle velocity of around 900 feet per second, but revised at the US government’s request to a 230-grain projectile of the same construction (FMJRN) at 830 to 850 fps. It did more or less what it was intended to do.

By the time that 10mm Auto was invented, people wanted an auto-loading cartridge that had more zing. 9mm (at the time) was considered anemic at best and .45 ACP – while serviceable – lacked the punch of .357 Magnum.

However, given that .45 ACP more or less did what it was invented to do the thought didn’t occur to too many people to just make it more powerful instead of inventing something totally new. The idea DID occur to Dean Grennell of “Guns and Ammo,” who invented the .45 Super. However, by the time he did so (which was in 1988) 10mm was already in production and pretty much nobody cared except for bowling pin shooters and hog hunters.

And herein layeth the point:

To push 10mm Auto to the original Norma load of a 200-grain projectile at 1200 fps (the original loading envisioned by Jeff Cooper was a 200-gr projectile at 1,000 fps, but so much for that) the 10mm Auto case has to be loaded with anywhere from 9 to 12.5 grains of powder, depending of course upon the powder being used.

Nosler’s Load Data indicates that 830 to 850 fps with .45 ACP 230-gr ball requires only 6 to 9 grains of powder, depending on the propellant used.

And why the heck does that matter?

The capacity of the 10mm Auto case is 24.1 grains of water, but holds 14 grains or less with projectiles of typical weight seated.

The case capacity of .45 ACP is 26.7 grains of water, holding 19 grains or less with projectiles of typical weight.

It is also the case that 10mm Auto generates chamber pressure, per SAAMI specifications, up to 37,500 pounds per square inch. .40 S&W, the Reader’s Digest version of 10mm, generates around 35,000 psi. Meanwhile, .45 ACP generates chamber pressures of 21,000 psi.

In other words, the original 200-gr loading of .45 ACP – at 900 fps – has ¾ the muzzle velocity of the original hot 10mm Auto loading, but generates slightly less than ⅗ the chamber pressure. Goosing the powder charge to .45 ACP +P bumps chamber pressure to 23,000 psi.

However, the effect is a net gain of anywhere from 100 to 200 fps of additional velocity. A 185-grain projectile that’s typically propelled to 950 to 1050 fps can be boosted to 1050 to 1150 fps. A 200-grain projectile, with the right powder, can easily be propelled to the 1000 fps velocity and 400 ft lbs+ called for by Jeff Cooper in creating the 10mm Auto.

To step up further to .45 Super, pressure increases to 28,000 psi but velocity of a 185-grain projectile reaches 1200 to 1300+ feet per second.

10mm Auto does, in fairness, have a slight advantage in terms of trajectory, but the difference in drop is less than an inch at 100 yards compared to .45 ACP+P or .45 Super.

In other words, a new cartridge and case weren’t needed. The Bren Ten wasn’t needed to get the performance he wanted. A few extra grains of powder in .45 ACP was all that was required, and the .45 ACP bullet and case could literally do everything 10mm asked for.

What this means, of course, is that if the public had asked for it, and the ammunition industry had obliged, .45 ACP could have been loaded to the exact same power level as 10mm Auto and therefore be used for literally every application that 10mm Auto is used for.

Which, of course, would mean less mechanical stress on the gun. As most of us are aware, higher-pressure cartridges are more punishing to firearms than lower-pressure cartridges. The chamber is worn out faster, and frames of semi-autos take more stress. Granted, your typical gun owner will never “shoot out” even a rifle barrel, let alone a handgun barrel but still.

And therefore, there’s less risk of the “Glock Kaboom” and less stress on the frame, such as that which required the relief cut on the Colt Delta Elite.

Would the cost per round increase? Possibly, but it would be modest. Starline Brass, for instance, charges an extra $10 per 500 cases for .45 ACP +P brass and an extra $20 for .45 Super brass compared to standard .45 ACP brass. The case has to have the case web, case head and case walls thickened, but the cost increase of course is rather modest.

Okay, so to bring this home:

Every desired attribute that 10mm has over .45 ACP can be realized with the .45 ACP case by just adding more powder, which can be easily done given the capacity. Not only that, but doing so comes at less cost in terms of mechanical stress on the gun and a minimal increase, if any, in materials.

Granted, there are some downsides. First is that there’s no reduction in recoil. Bullets that have different diameters but are of the same grain weight and are propelled to similar velocities from a gun of the same weight produce more or less the recoil force, since recoil force – which is different from perceived recoil – is a function of projectile weight, projectile velocity, and the mass of the gun.

Have a look at rifle recoil tables and it’s the same story. The recoil force is near as makes no difference the same for an 8-lb rifle firing a 150-gr bullet at 2700 to 3000 fps regardless if it’s a .270 Winchester, .280 Remington, .284 Winchester, .308 or a .30-06.

That said, a lighter grain weight – say a 165-grain projectile – at velocity of or below 1000 fps would produce recoil force similar to .40 S&W, which is certainly tolerable in a compact to full-size pistol.

Another downside, of course, is the capacity. You just can’t stuff that many rounds of .45 ACP, being a big fat bullet, into a handgun and especially if you want to be able to carry it – concealed or otherwise – and do so comfortably.

10mm generally adds 1 more round of capacity, possibly 2 depending on the magazine; .40 S&W not only adds at least +2 of capacity but also reduces the size of the frame, which makes the gun more easily handled by those with smaller hands (which is what caused the FBI to drop 10mm as much as the recoil was) as well practicable to make in a slim, subcompact form factor.

However, those shortcomings aside, it can be said that the .45 family is vastly more capable, as it is capable of both softer-shooting loadings as well as – for all intents and purposes – semi-auto magnum velocity and energy levels, as .45 ACP+P and .45 Super loadings duplicate the energy levels of 10mm and exceed those of .357 Magnum, and do so at less than 30,000 psi of chamber pressure.

Disagree? Don’t care? Just came here for an argument? Sound off in the comments.

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Sam Hoober is a Contributing Editor to, a subsidiary of Hayden, ID, based Tedder Industries, where he writes about gun accessories, gun safety, open and concealed carry tips. Click here to visit