Armalite Rifle gas systems

[Vincent]

Can anyone tell me if the AR-18, AR-180 and AR-180B have identical gas systems? Will all the gas system parts interchange?

Information

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[fjruple]

Vincent--

I cannot speak for the AR-180B but the AR-18 and AR-180 gas systems are identical.

--fjruple

[Peter Laidler]

AR gas systems...... We never saw an AR15 in Australia but we knew that they were coming to us in Malaya shortly after I got there so the whole idea was totally new to us. I couldn't believe it when I saw one....., a gas system without a piston and gas that just went into the whatsit and was scraped by rings and......... It was like science fiction. A learn as you went along sort of thing. I went on a course at 40 Base Workshop and met up with some other Brit, Aust and NZ Armourers who had used them up country and in action in SVn. Our instructor, Mr Amto told us all that he was learning it from US...., it was so new to us. One of the jungle warfare bosses (I met him again at Warmninster many years later) joined the class and gave us the practical lowdown. They'd used them against live goats that lived through it! We really didn't see how they would replace shotguns. We also had special kits to repair the plastic butts and handguards because spare parts were not available initially. It was a fast learning curve....... In a year we had thousands of them.

[tiriaq]

The 180B has some parts commonality with the 18 and 180, but I do not know if this extends to the gas system.
With respect to the AR-15 type rifles...
The term DI - Direct Impingement - is often bandied about in reference to the gas operating system.
Rifles like the AG42B, French 49s, have direct impingement systems. There is a little spigot which engages the bolt carrier; the carrier is blown back.
The term was first applied to the AR way back when it was first being introduced. A Colt executive who did not understand how the AR worked used the term to describe and promote the rifle. He did not understand that the gas is ducted back into the bolt carrier. Got that tidbit from a senior Colt Canada armourer.

[Vincent]

Vincent--

I cannot speak for the AR-180B but the AR-18 and AR-180 gas systems are identical.

--fjruple

Thanks, fjruple.

I never wanted an AR-18 or AR-180. To be honest, I couldn’t even look at them. But my local gun shop called and said he had a “Sterling.” I was surprised when I got there to see it was an Armalite, an AR-180 made under license in England by Sterling.

It has seen better days and some parts are missing including the op rod, spring, link and piston. But for a stamped sheet metal gun, it’s really quite well designed and made.

I couldn't believe it when I saw one....., a gas system without a piston and gas that just went into the whatsit and was scraped by rings and......... It was like science fiction.

Yeah! In my mind, it’s like having a car’s exhaust pipe end in the passenger cabin. You’re putting dirty gas just where you don’t want it. But it’s cheap, saves a little weight………. and did I mention it’s cheap?

Piston driven gas systems have found their way into a lot of Armalite variants. There are also piston conversion kits available.

BTW, I just reread the AR-180 section in your GoD book. Good info on serial numbers etc.

[fjruple]

Vincent--

I have shot the AR-18 on numerous occasions and have owned a Costa Mesa and Howa built semi auto version of the AR-18 the AR-180. Gene Stoner went to the gas piston system in AR-16 (7.62mm NATO) and AR-18 (5.56mm) due to heat and carbon build up in the bolt carrier. The AR16/AR-18 was developed for production in countries that did not have a lot of machine tools but did have metal stamping capabilities.

--fjruple

[Vincent]

From what I can tell, the link, rod and spring are the same on the AR-180B, but the piston and cylinder are different.