Rufus writes:

This is a picture of my original Armalite AR-180 manufactured in England by Sterling.  I saw it in a shop next to one of the new ones produced by the current Armalite (which is the same company in name only) with the polymer lower.  I fell in love with the spot-welded, industrial ugliness of the original.

The rifle is popped open for field stripping and the moving parts can be seen above.  They’re quite similar to an AR-15, except that the firing pin is held in by a pin instead of a cotter pin.  Additionally, the cam pin rides on the side of the bolt carrier opposite the ejection port instead of on top of the carrier in the AR-15.  A similar arrangement is used in the G-36 and SCAR.  The firing pin is spring-loaded.

You can see a bit of a gap between the upper and lower handguards because the return spring guide rods are responsible for holding on to the upper handguard!

Interesting rifles to be sure.”