10mm Ammo

10mm Auto: In Depth

Now serving as a brilliant bear and hog smasher at the side of many a bushwhacker, this cartridge began life in the early 1980s as a more robust alternative to the anemic 9mm loadings available at the time. The early years of 10mm Auto were full of excitement – a brand new pistol and cartridge, Miami Vice, the roller coaster FBI adoption and subsequent abandonment – even hallowed handgun luminary Jeff Cooper is part of the story! Even so, by the 1990s, the 10mm Auto had quickly taken a backseat to the upstart .40 S&W – a fate that surely incensed its inventors. However, in time, what may have doomed the cartridge in the short term has proven to be its lasting salvation: power. Oh, and it feeds through a semi-auto, too.

10mm Auto: History

In 1980, a small firearms manufacturing partnership known as Dornaus and Dixon reached out to famed handgunner, instructor, and small-arms master Jeff Cooper for assistance in the development of a new pistol and powerful new cartridge to match. This gun – what ultimately became the Bren Ten, and the cartridge – the 10mm Auto, emerged shortly thereafter as a solution to the problem plaguing every autoloader of the day: not enough penetration. For the new round, the creators envisioned a beefy case, a stout charge, and a generously-sized .40 caliber bullet sitting on top; something with magnum power, capable of slinging a 200-grain bullet in excess of 1,200/fps, yet designed to function flawlessly in a semi-auto pistol. 

The resulting pistol and cartridge were released in 1983, with Norma of Sweden providing the initial loading of a 200-grain JTC (Jacketed Truncated Cone) bullet, dialed up to 1,200/fps. 

Although the mid 80s saw a short spike in sales after the Bren Ten was featured in early episodes of TV’s Miami Vice, this didn’t prevent Dornaus and Dixon from declaring bankruptcy and ceasing production of the Bren Ten a mere three years later, in 1986.

Around the same time, the frantic aftermath of a wild shootout would lead the outgunned FBI to search for a new service cartridge. In 1989, although employing a greatly reduced loading (180-grain JHP @ 975/fps) due to the considerable recoil inherent in the full-house loads, the FBI adopted the 10mm Auto, along with the S&W Model 1076 semi-auto pistol shortly thereafter. 

Almost immediately, however, the FBI found that they could reproduce the ballistics of their much-weakened 10mm Auto load with a shortened case – short enough to squeeze it into smaller-framed handguns originally designed to carry 9mm Luger – and then plunking the same .40 caliber bullet on top. Enter the .40 S&W: a cartridge that quickly sidelined its 10mm sibling for the next twenty years. 

Throughout the 1990s, law enforcement organizations across the US adopted the .40 S&W in droves, and the 10mm Auto continued to fade in popularity.

Nevertheless, due to its massive power and case capacity (and the fact that Glock chambered a pistol for the cartridge), the 10mm Auto steamed on, undeterred. It was a natural choice for defense against wildland predators, and the variety of loadings proved to be an asset for tactical units, two-legged self defense, and competition shooting alike. Couple those reasons with the strong desire to clown on .40 S&W endemic to the gun community over the years, and a healthy explanation emerges for the popularity and persistence of this round.

10mm Auto Guns

Now we will cover some of the most popular 10mm Auto weapons, over the years.

Early Pistols

Taking inspiration from the CZ-75, the Bren Ten pistol was the first to be chambered in 10mm Auto, and was only manufactured for a few years (1983-1986). The Colt Delta Elite arrived in 1987 – the first of many M1911 variants chambered in the cartridge. Smith and Wesson’s Model 1076 was adopted by the FBI for a short time in 1990. The first Glock to use the 10mm Auto chambering, the Model 20, has been a perennial top seller since its introduction in 1991.

• D&D Bren Ten  
• Colt Delta Elite 
• Smith and Wesson Model 1076 
• Glock 20  

Current Pistols

Many current manufacturers offer pistols chambered in 10mm Auto; steel M1911 variants and polymer framed-pistols are both commonly found.

• Dan Wesson RZ-10 Razorback
• Kimber Eclipse Custom II
• PSA Admiral
• Sig P320 X-TEN 
• Smith and Wesson M&P 2.0 10mm
• Glock 40

Why 10mm Auto?

The cartridge was designed to combine magnum power with a semi-auto platform. Although some 10mm Auto loadings have significant recoil when compared with 9mm Luger and even .45 ACP, shooters who are prepared to deal with the extra oomph have a ballistic solution that is far more effective than those cartridges at longer distances while still offering numerous follow-up shots.

Hunting

• Simply put, 10mm Auto delivers more power downrange than almost any other semi-auto handgun cartridge, and even some magnum wheelgun rounds.The tradeoff vs. hunting with something like a .44 Rem Mag (which is more powerful), for example, being increased round capacity.
• Many ammunition manufacturers offer hunting-specific loads in 10mm Auto, and with proper shot placement, taking deer-sized game is no problem.

Self Defense

• The cartridge was developed with law enforcement in mind, and the guns themselves were designed from day one to feed hollow-point ammunition reliably. 
• Perhaps the most enduring use case for 10mm Auto is defense against large critters such as bears.

Target / Competition

• Although more costly to feed than 9mm Luger counterparts, 10mm Auto pistols are incredibly satisfying to shoot at the range, and flatter shooting than 9mm by far.

10mm Ammo Brands and Loadings

Due to its generously-sized case, the 10mm Auto is a no-brainer if you’re looking to stomp butts with a semi-auto. The “standard” 180-grain FMJ/JHP @ 1,200/fps loading is only one of many, however; there are specific loads for every need. 

The Beginning 

• The first commercially available ammo offering was a 200-grain JTC from Norma @ 1,200/fps.
• This was followed shortly by a 170-grain JHP @ 1,300/fps, also from Norma.
• Standard loading became a 180-grain TMJ/FMJ-FN/TC or 180-grain JHP @ 1,200/fps.

Modern Loadings

• Common grain weights range from 130 up to 220 and higher.
• Advertised velocities range from below 1,000/fps to 1,300/fps and above.
• Nearly every major manufacturer offers a 180-grain option, either in FMJ-FN or JHP @ approx. 1,200/fps.
• Hunting-specific ammo is available with monolithic solid, heavy bonded, and soft-point bullets to suit many types of game. 
• Self-defense ammo is commonly available with 170-grain and 180-grain JHP bullets, though some manufacturers offer bullets that are lighter or heavier for caliber.
• Critter defense ammo largely using hard cast lead bullets

Brands

• US Manufacturers include: Federal, CCI (Blazer), Winchester, Remington, Hornady, Underwood, Buffalo Bore, Lehigh Defense, and more.
• Imports include: S&B (Sellier and Bellot), PPU (Prvi Partizan), PMC, Aguila, and more.

Bullet Types

In a cartridge designed for deep penetration like this one, most 10mm Auto bullets will perform a number of roles well. Here are some general use recommendations for the most commonly-available bullet types:

• FMJ / TMJ (Full Metal Jacket / Total Metal Jacket) - Target shooting, training

• JHP (Jacketed Hollow Point) - Self defense

• Hard Cast Lead - Bear defense 

• Monolithic Solid / Penetrator - Hunting, self defense

• JSP (Jacketed Soft Point Lead) - Hunting

Bullet Profiles

• Most 10mm Auto ammunition employs a “flat nose” (FN), sometimes called “truncated cone” (TC) bullet to keep OAL (overall length) down; therefore able to fit into magazines (and also to keep handgun frame sizes reasonable). 
• JHP bullets exhibit the same clipped-end shape.

Bullet Weight

10mm Auto ammunition, while commonly loaded somewhere between 130-grains to 220-grains, can be found with especially light or heavy bullets outside of this range as well, with manufacturers offering these varieties:

• Solids - 130-grain to 150-grain 
• JHP - 150-grain to 180-grain 
• FMJ - 180-grain to 200-grain 
• Soft Point / Hard Cast Lead - 200-grain to 220-grain 

Velocity

• Standard velocity for 180-grain FMJ target load is around 1,200/fps.
• The fastest loads feature lighter-weight bullets in the 130-grain to 150-grain range, which really get cookin’ at 1,400/fps to 1,500/fps! 
• The heavier-for-caliber soft point and hard cast lead loads generally have the same muzzle velocity as the 180-grain target loads (~1,200/fps) but are instead propelling a monster 200 or 220-grain bullet, which translates into ~650-700 ft/lbs at the muzzle. That is some serious energy!