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.
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.