9mm vs .223 Ammunition

Find out how your home-defense ammo stacks up against today’s criminal element.

When trouble comes through the door, the savvy homeowner is fully armed with the proper hardware, information, and self-defense training. Ichiro Nagata Photo

Prudent homeowners understand that the best form of defense for themselves and their families against assault is a firearm. I was privy to a conversation at a local gun shop where a man was pondering the purchase of a long gun for home protection. He had just about convinced himself to buy an AR platform carbine, but was having second thoughts about the .223 Remington cartridge and whether or not it was “safe” to use inside a home. Specifically, he was worried about over-penetration. He was considering an AR carbine chambered in 9mm instead of .223.

To the casual reader this might seem like a very reasonable compromise. Surely the 9x19mm pistol cartridge would represent a reduced over-penetration hazard when compared to the .223 Remington centerfire rifle round. My goal in this review would be to compare the two from a ballistic standpoint, as well as provide a realistic downrange damage assessment.

The Contenders
For this review it seemed logical to secure both a 9x19mm carbine and nearly identical version in .223 Remington. CMMG, Inc. of Fayette, Missouri, happened to have a near matching set in both calibers.

Presented for your consideration are M4 style carbines with 16-inch barrels. One model chambers the 5.56mm/.223 Remington round and the other the 9x19mm round. Both have flat-top receivers, 4-way rail aluminum forearms, and retractable stocks.

The free-floating 5.56mm barrel has 1 in 7 right hand twist rifling. The 9mm version used 1 in 10 rifling. Both barrels were capped with a NATO-style birdcage flash suppressor. Also, each carbine used a Picatinny rail gas block.
As for operation, the 5.56mm model was CMMG’s new gas-piston carbine and the 9mm version used a straight blowback, recoil-operated mechanism. All external controls for both carbines were standard AR configuration, including the bolt catch, magazine release button, manual safety lever and trigger.

Lower receivers varied in that the 5.56mm model used a standard AR configuration and was fed by all AR style magazines. The 9mm lower was a dedicated receiver, not a plugged or modified AR-type. Metalform 32-round stick magazines fed the 9mm carbine.

For sights, I installed the new EOTech XPS3 HWS on each one. The XPS3 uses only one CR123 Lithium battery and is more compact than older models. The dual “circle and dot” reticle was used. These sights were zeroed a practical range of 50 yards.

The ammunition for this review would be that specifically designed from personal protection. Training and target ammunition are great for the range, but when it really counts we need to spend the cash on high quality ammo designed for the task at hand.
Both CMMG carbines that were tested use four-way aluminum rail systems.

Load Comments
  • guavabreeze

    A 12 guage pump or a .357 Mag are my 1st choices for home defense

  • zac

    this proves they didnt know much about guns or bullets in general, the 9mm will over penetrate before a 5.56, if you dont believe it look it up, most swatt teams and police are trading in MP5s just because of this reason, the 5.56 shatters most of the time when it hits a solid object like a concrete wall, there is 5.56 ammo that will penetrate tho, the black tipped rounds are made to penetrate, the standard wont, this also comes down to barrel length, they say a 5.56 is no good out of a short barreled rifle, that you end up have to rely on .22 caliber wholes because it does reach a velocity to fragment and tumble properly, the 9mm is a big whole all the time no matter what, it wasnt designed to rely on fragmentation and tumbling, it relies on expansion, for close range self defense, 9mm, if you do go 5.56 or .223, use hollow points if you have a short barreled rifle, use fmj if you have at least a 14.5 in barrel and up, but i will say ive talked to a man whose been shot in the line of duty, with both a .308 and 5.56, he claims he couldnt tell a difference he went down both times and luckily survived, so who knows, but a 5.56 will not over penetrate, and even tho a 9mm will penetrate it would never penetrate multiple walls and fly off a 500 yards hitting an innocent person, it just dont happen

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  • I appreciate the article. I learned a lot! I am new at to the sport of shooting. I was considering buying a 9mm carbine (Bushmaster) because I am also going to buy my wife a Glock 17. I thought it would be more practical to have the same ammunition. I’m not really interested in hunting, as some do with carbines. I am interested practicality, as I said, cost of ammunition, accuracy and personal defense.

    I also appreciated some of the opinions of the readers who responded to the article, especially the point regarding FMJ vs non-FMJ rounds. I’m not an expert but that made perfect sense to me. Why didn’t you choose more similar ammunition. The results may have more similar. It which case who cares about muzzle velocity if both bullets produce the same result a dead home intruder.

    Not to beat a dead horse but what if the rounds you tested were more similar and both penetrated the to approximately the same depth of a human body they would both be at about in the middle of a human heart or an aorta provided you hit the target at center mass.



  • peblair

    If you DON’T want penetration through interior walls, by GLASER ammo.

  • Joakim Henrikson

    Will this debate never die? I remember 20years ago when everybody said that ”the nine” just didn’t cut it at all, I HAD to be 357magnum, or you where doomed! Well it could be OK if was a .45 but NO WAY a nine! We have seen this debate since .30 carbine in the little M1 Carbine was declared useless, funny ha? Still more M1 Carbines out there in service than the 30.06 M1 Garand’s everybody swore by, and later it was the M14 vs. the ”Mickey Mouse Mattel” rifle, well we all know what happened there. So, a high speed light bullet vs. a lower speed heavy bullet. Well here is the bare truth without getting in to details and specific bullet designs. Which one makes you hit better? Has the lightest recoil? Lowest muzzle flash? Which weapon can safely be used by YOU? This isn’t about which calibre, hell it’s not even about what type of weapon it is! It’s about WHO is using it and WHERE and how PROFICIENT the user is, first! Then understand the limitations of YOUR system adapt to it and over come these problems with knowledge and skills. Home defence issues don’t stop or even start with issues such as over penetrations alone. If you only have one set of tools you adapt the whole situation accordingly! Or, change the situation so that it suits YOU. If you live in a ‘’hood’’ where you need a fast shooting carbine then you FIRST need to create sufficient cover! If not for your self then for your loved ones, then its time to start worrying about over penetration or not and what calibre or tool to use, and there are special solutions for both the 9mmP and .223. Should none of them work for you, get a shotgun!

  • George

    Hey Mike Reed ,
    What the didn’t hit on was bullet style & weight the .223 60gr test bullet while it is a rifle round the bullet is designed to fragment on impact. If a fmj bullet had been used it would of had considerably more penetration. The 9mm shooting a 115gr to 124gr bullet no matter if it’s fmj or hollow point will penetrate more than a 55gr to 60gr that is designed to break apart on impact it’s just a matter of the bullet design and weight being used

  • Oz

    Very informative article, we need more like it!

  • Jess

    Mike, The way I read it, both were from carbines.

  • Mike Reed

    Did I read that right? The 9mm penetrated twice as far as the 223? If true, then pistols have a greater chance of over penetrating than rifles. That seems counter intuitive. Still, I recall an episode of Mythbusters that found pistol bullets were more likely to penetrate pool water and strike a swimmer than rifle rounds.

  • Ron

    Buy a shotgun

  • Jay C.

    Nice article.