AR-18 magazine ?

[AmEngRifles]

I am no expert. But have been collecting and observing original Armalite AR-180 products for some time. Here is my interpretation.

I believe you have a Costa Mesa contracted magazine. I say "contracted", because I have NO idea if the Costa Mesa facility that produced the weapons ever made the magazines? The may have simply contracted them out with a supplier? Obviously the early date would indicate a mag made just prior to manufacturing going to Howa of Japan. I have NEVER seen one in a military grade VOC paper package. WOW! These early magazines have NO identifying marks, and I am not sure why they choose to not mark them? I am unclear about magazines produced for Howa made rifles. I have never run across a NIB Howa 180 with all the factory supplied accessories.

The later, Sterling produced, mags have a longer engagement slot. Sterling mags have base plates that I.D. them. Be aware though, base plates can be switched out, and that can lead to some erroneous mag I.D.s if you aren't careful. You may find (if you have other manufactured models to test against) that your mag will not fit a Howa or Sterling. I have found that the the various manufacturers have small difference in mag slot length and all mags will not fit all rifles.

A note about those mags that ONLY have the AR-18/0 slot. It is mostly the 20 round early ALUMINUM mags (I believe made by Costa Mesa Armalite). All steel mags of 20, 30 and 40 made by Sterling or Costa Mesa Armalite have BOTH slots. That is, they have the AR-180 slot and the AR-15 slot. Another exception to the rule is the Thermold mags out there that are made for the AR-180. They will not have an AR-15 mag slot. I am unclear why Thermold just didn't incorporate BOTH mag slots into the same mag?

The steel Armalite mags have a very good reputation for reliability. Up until H&K high reliability mags hit the market, the steel Armalite mags had a enthusiastic following. This includes the Sterling made steel mags of all capacities. All this get's quite confusing, because unless you have been playing in this arena for 40 plus years, the crap mags put out by USA, and other inferior manufacturers, get confused easily by newer collectors.