10mm Is Coming Back and is Smart for PCC - Pistol Caliber Carbines
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If you know the background development of the 10mm round, you might know that it was developed as a high power semi-auto round ultimately selected by the FBI. The problem was that the 10mm round was actually too powerful for the majority of the agents to actually carry, train with and shoot comfortably.
The 10mm round has a cult following that is increasing with the Glock G20 still being a strong seller and other manufacturers like Rock Island, Para, Wilson, Sig, Kimber, and others all offering 10mm models as well. With the popularity of PCC - pistol caliber carbines, the 10mm power makes a huge amount of sense for very short PDW type pistols.
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BRIEF HISTORY OF THE 10MM AUTO
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The development of the 10mm round is actually an interesting story which dates back to the 1970s. The idea was for a high power flat shooting semi-auto cartridge that would run in a 1911 format pistol which would basically deliver .357 to .44 Magnum (midweight loads) ballistics. In the end, Jeff Cooper, yes the scout rifle guy, was involved in the development at which point Norma began producing ammunition in the early 1980s. The FBI felt a little outgunned on the streets and briefly adopted the 10mm round, but with the full bore kick ass loads that were first released, they felt it was just too much.
The reality was 90% of the agents felt uncomfortable shooting and handling the larger dimensioned and significantly more powerful 10mm powered guns. The ammo manufacturers responded with the 10mm Lite rounds which in essence dropped the power all the way down to really hot .40 S&W loads around 550 ft/lbs of energy at the muzzle.
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The FBI and the public wanted a smaller format with less power than what the 10mm round delivered. Smith & Wesson thought this was a waste of unused powder space on the longer 10mm brass and developed a 10mm Short or what we now know as the .40 S&W. The round delivered everything the FBI specs wanted in a format that would fit in a smaller 9mm sized pistol format.
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The current crop of 10mm rounds from Hornady and others are not neutered to the degree the "LITE" rounds were, however they could certainly be loaded hotter as we see with the higher power 1,350fps and 728 ft. lbs of energy Buffalo Bore rounds and the very unique LIbery Ammo with a 60gr bullet screaming along a 2400 fps delivering a whopping 780 ft/lbs. The current neutered 550 ft/lbs of energy 10mm rounds are still much more powerful than the average 360 ft/lbs of energy found in the .40 S&W. .40 S&W usually deliver around 360 Ft/lbs of energy and the normal off the shelf 10mm Auto loads typically delivery around 550 ft/lbs which is nearly 40% more power.
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Today the 10mm cartridge still does have a following in Special forces and Special Law Enforcement and is growing as a hunting cartridge due to the capacity of the firearm and power. It is a favorite pistol for those hunting hogs and venturing into bear country.
5.56 7-inch Barrel vs 4-inch barrel 10MM
The 5.56 round is a wonderfully flexible round, however as with most shouldered cartridge rifle rounds, they are optimized for longer barrels and lose a ton of velocity with barrel lengths under 10-inches. In the case of a 5.56 7-inch AR15 pistol muzzle velocity and energy take a huge hit down to 2000-2200 fps velocity and 500-700 ft/lbs energy. A super short AR15 still delivers big power, but in contrast the 10mm is actually a better option.
Depending on the round, 10mm rounds were designed to deliver 500-770 ft/lbs energy and 1000-2400 fps out of a 4-inch barrel and out of an AR15 equivalent 7-inch barrel the round picks up about another 10% of velocity and a bump in power. The heavy fat round is designed as a pistol caliber which means it really will not pick up a lot more power with a longer barrel, where the light 5.56 round loses about half of its power in a 7-inch barrel. Of course there is also that deafening concussive blast out of a 7-inch barreled 5.56 AR15 pistol which makes it really impractical for home defense. With these points in mind, the argument could easily be made that a very compact 10mm PCC with a 4-inch barrel has the same or more power, in a smaller & quieter format, and that also accepts G20 pistol magazines is a better choice in micro PDW formats.
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The 10mm PCC build pictured is based on a Glock G20 magazine compatible New Frontier Armory receiver set & .40 Caliber bolt, KAK 4-inch 10mm barrel, SB tactical brace, Hiperfire EDC trigger and Sig Sauer Romeo 5 red dot. At under 20-inches, this little PCC is a thumper and can get my steel targets rocking - a feat any of my AR15s cannot accomplish. With a LAW Tactical folding stock adapter instead of the SB Tactical brace, this little rig could be under 14-inches.
If you are not in the mood to build your own, New Frontier and others offer complete 10mm uppers and C45 lowers that have a combined cost of just under $1000 that only require you to push in the take-down pins. Retailers like Joe Bob Outfitters also have a variety of options as well for a DIY option at a reduced price.
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If you know the background development of the 10mm round, you might know that it was developed as a high power semi-auto round ultimately selected by the FBI. The problem was that the 10mm round was actually too powerful for the majority of the agents to actually carry, train with and shoot comfortably. The 10mm round has a cult following that is increasing with the Glock G20 still being a strong seller and other manufacturers like Rock Island, Para, Wilson, Sig, Kimber, and others all offering 10mm models as well. With the popularity of PCC - pistol caliber carbines, the 10mm power makes a huge amount of sense for very short PDW type pistols.
BRIEF HISTORY OF THE 10MM AUTO
The development of the 10mm round is actually an interesting story which dates back to the 1970s. The idea was for a high power flat shooting semi-auto cartridge that would run in a 1911 format pistol which would basically deliver .357 to .44 Magnum (midweight loads) ballistics. In the end, Jeff Cooper, yes the scout rifle guy, was involved in the development at which point Norma began producing ammunition in the early 1980s. The FBI felt a little outgunned on the streets and briefly adopted the 10mm round, but with the full bore kick ass loads that were first released, they felt it was just too much. The reality was 90% of the agents felt uncomfortable shooting and handling the larger dimensioned and significantly more powerful 10mm powered guns. The ammo manufacturers responded with the 10mm Lite rounds which in essence dropped the power all the way down to really hot .40 S&W loads around 550 ft/lbs of energy at the muzzle.
The FBI and the public wanted a smaller format with less power than what the 10mm round delivered. Smith & Wesson thought this was a waste of unused powder space on the longer 10mm brass and developed a 10mm Short or what we now know as the .40 S&W. The round delivered everything the FBI specs wanted in a format that would fit in a smaller 9mm sized pistol format.
The current crop of 10mm rounds from Hornady and others are not neutered to the degree the "LITE" rounds were, however they could certainly be loaded hotter as we see with the higher power 1,350fps and 728 ft. lbs of energy Buffalo Bore rounds and the very unique LIbery Ammo with a 60gr bullet screaming along a 2400 fps delivering a whopping 780 ft/lbs. The current neutered 550 ft/lbs of energy 10mm rounds are still much more powerful than the average 360 ft/lbs of energy found in the .40 S&W. .40 S&W usually deliver around 360 Ft/lbs of energy and the normal off the shelf 10mm Auto loads typically delivery around 550 ft/lbs which is nearly 40% more power. 
Today the 10mm cartridge still does have a following in Special forces and Special Law Enforcement and is growing as a hunting cartridge due to the capacity of the firearm and power. It is a favorite pistol for those hunting hogs and venturing into bear country.
5.56 7-inch Barrel vs 4-inch barrel 10MM
The 5.56 round is a wonderfully flexible round, however as with most shouldered cartridge rifle rounds, they are optimized for longer barrels and lose a ton of velocity with barrel lengths under 10-inches. In the case of a 5.56 7-inch AR15 pistol muzzle velocity and energy take a huge hit down to 2000-2200 fps velocity and 500-700 ft/lbs energy. A super short AR15 still delivers big power, but in contrast the 10mm is actually a better option.
Depending on the round, 10mm rounds were designed to deliver 500-770 ft/lbs energy and 1000-2400 fps out of a 4-inch barrel and out of an AR15 equivalent 7-inch barrel the round picks up about another 10% of velocity and a bump in power. The heavy fat round is designed as a pistol caliber which means it really will not pick up a lot more power with a longer barrel, where the light 5.56 round loses about half of its power in a 7-inch barrel. Of course there is also that deafening concussive blast out of a 7-inch barreled 5.56 AR15 pistol which makes it really impractical for home defense. With these points in mind, the argument could easily be made that a very compact 10mm PCC with a 4-inch barrel has the same or more power, in a smaller & quieter format, and that also accepts G20 pistol magazines is a better choice in micro PDW formats.
The 10mm PCC build pictured is based on a Glock G20 magazine compatible New Frontier Armory receiver set & .40 Caliber bolt, KAK 4-inch 10mm barrel, SB tactical brace, Hiperfire EDC trigger and Sig Sauer Romeo 5 red dot. At under 20-inches, this little PCC is a thumper and can get my steel targets rocking - a feat any of my AR15s cannot accomplish. With a LAW Tactical folding stock adapter instead of the SB Tactical brace, this little rig could be under 14-inches.
If you are not in the mood to build your own, New Frontier and others offer complete 10mm uppers and C45 lowers that have a combined cost of just under $1000 that only require you to push in the take-down pins. Retailers like Joe Bob Outfitters also have a variety of options as well for a DIY option at a reduced price.
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