Early Capacity

Early on the plan at Armalite was for their new 5.56 rifle to have a 25-round magazine.

Because of round taper, this plan didn't work out and 20-rounds was settled on until the late-60's.

Thanks to Brownell's, I can now compare the pre-'67 AR magazines.

From left to right:

25-round straight magazine, 20-round "waffle" magazine, 20-round USGI magazine, early 30-round USGI magazine.

Word has it that the 25-round reproduction is a bit long compared to the original and that a USGI 30-round spring is stuffed in there.

Rumor confirmed!  A USGI spring wouldn't fit into an OG 25-rounder without cutting a couple coils.  Also notice the center spike of the follower is shortened from the old all-tilt black follower.

It looks decidedly odd in a mag-well though.

The next development was what is now known as the "waffle" magazine, based on scaling down the "waffle" pattern magazine of the AR-10.

The reputation of the waffle mag is bad.  It earned an unenviable reputation for being unreliable because of an early design decision.  Armalite anticipated that these thin, steel aluminum magazines would be shipped, loaded, in the crates and discarded when empty.

The Air Force and Army don't do things like that and so reused the magazines.

Because they weren't designed to be durable, they didn't work well for long.

By the time Vietnam rolls around, the Army was aggressively pursuing extant waffle mags for destruction and getting the new, aluminum, 20-rounders into the hands of the troops.

The 20-rounder wasn't a complete cure.  You can stuff 21 rounds into one easily, and 22 if you really try.  This over compresses the spring and weakens it, making the mag unreliable.  If you never ever load more than 20 it's pretty solid, and you only load 18, it will last a lifetime.  Well, until the feed lips wear out...

It wasn't long before the troops wanted the same number of rounds the bad guys had, which leads to the 30-rounder I've yapped about before.