How the AR-18 Influenced Modern Rifle Design

As far as Armalite is concerned, the AR-18 was a bit of a failure. They were flying high on the AR-15 and the US adoption of the weapon. Okay, well, not really, since they sold the design to Colt to keep the lights on. Armalite wanted another hit, and this time, they wanted the sweet, sweet cash, so they developed the AR-18. They knew Colt would chase them down with lawyers if the design was close to the AR-15. 

This forced them to be creative. Eugene Stoner created the AR-16 in 7.62 NATO, and Armalite took that design and shrunk it to a 5.56 platform. They also knew that if they planned to sell this as a service rifle, they’d need to be capable of mass production. Mass production is tough, so Armalite didn’t plan to mass produce the gun. Instead, they wanted to sell a license to produce the gun to countries that adopted it. 


The AR-18 was designed to provide lower-budget military forces with a modern, easy-to-produce 5.56-caliber assault rifle. The rifle would be cheap to construct and use stampings and welding. It wasn’t as refined as the AR-15 but could provide a modern select-fire 5.56 rifle on the cheap. 

Inside the AR-18 

The AR-18 had to avoid the direct impingement system and went with the proven short-stroke gas piston design. The AR-18 wasn’t the first short-stroke gas piston system. That award goes to the M1 Carbine. While both guns use a short-stroke gas piston system, the AR-18s significantly differed from the M1 Carbine. The M1 Carbine had to utilize a light rifle cartridge, and the AR-18 had to use a much higher-pressure cartridge. 

Additionally, the bolt design, piston placement, and gas trap are all considerably different from the M1 Carbine. The bolt wasn’t all that different from the AR-style bolt with seven locking lugs. Instead of receiver extension and buffer and buffer spring, the gun rides on dual recoil springs inside the receiver. This does allow for folding stocks. 

The cocking handle reincorporates and is directly connected to the bolt. Much like the AR, the weapon was well-sealed from dirt and debris. The rifle broke down into an upper and lower receiver group and could break open like a shotgun for easy field stripping. Overall, it was a seemingly decent rifle. The weapon proved reliable, accurate, and easy to shoot, but it was never a major success. 

Howa of Japan obtained a license to produce the gun, and Sterling Armaments Company of the United Kingdom also produced the gun under license. The Philippines dabbled with the design, but it seemingly went nowhere. Armalite was sold, and the AR-18 would have been another interesting but nearly forgotten rifle in Armalite’s history. 

Yet, the gun lived on, mostly through other guns. 

The Influential Nature of the AR-18 

Forget about the AR-15 and AKM for a moment. I want you to name five other intermediate caliber semi-auto or assault rifles. Just name five. I bet at least three of those take inspiration from the AR-18. In fact, it’s easy for all five to have inspiration from the AR-18. Guns like the Steyr AUG, the G36, the CZ BREN, the SCAR, the HK 433, the FN F2000, and even rifles from China like the QBZ-95. 

Observer the AR-18 bolt (

That’s only a partial list, by the way. There are way more guns out there that took inspiration from the AR-18 than I’ve listed. Most of these guns take inspiration from the short-stroke gas piston system plugged into the AR-18. Specifically, look at the bolts in any of the rifles listed above. The G36, the AUG, etc, all have bolt and bolt carrier designs that are remarkably similar to the AR-18. The gas piston system is also placed above the barrel of these guns, just like the AR-18. 

Now look at the G36 BCG (HKPROs Forum)

This specific gas system works insanely well with high-pressure intermediate cartridges. It’s reliable, proven, and also affordable to produce without sacrificing anything. Beyond just working the gas piston system works exceptionally well with suppressors and short barrels, these are both modern needs that have infiltrated small arms design in the last decade. 

If you need to make a modern rifle for a Western military force, then the AR-18 is likely your starting point. I’m not saying these rifles don’t have their advantages or are just rip-offs because they aren’t. Just using the AR-18 system doesn’t guarantee success. The SA-80 series used the same short-stroke gas system, and it performed terribly. 

The American AK 

The legend or the Armalite Rifle 18 has always reminded me of the American Ak. It was rugged, reliable, and cheap to produce once you had the machinery to do so. Sadly, it didn’t have the staying power of the AK, but it had a similar influence. Thankfully Brownells produced the BRN-180 series so we can all get a little AR-18 love. 

Travis Pike
Travis Pike is a former Marine Machine gunner who served with 2nd Bn 2nd Marines for 5 years. He deployed in 2009 to Afghanistan and again in 2011 with the 22nd MEU(SOC) during a record setting 11 months at sea. He’s trained with the Romanian Army, the Spanish Marines, the Emirate Marines and the Afghan National Army. He serves as an NRA certified pistol instructor and teaches concealed carry classes.