I have an original ArmaLite 20 rd AR-15 magazine, marked "CAL .223".  I undertand these were the first AR magazines made, and are quite rare.  Could anyone tell me what the value would be on this magazine??

absolutely worth less as a matter of fact their so worth less I would be willin to take that off your hands a dispose of it for no charge to you at all (except shipping of course). [:D]

Make sure it's not an AR-18 mag that someone home modded.. Early ones had a distinctive horizontal, and vertical pattern of reinforcing ribs in the body, as compared to the common vertical only..
 Posting piccies would help..

Meplat-

It is an actual ArmaLite AR-15 magazine, as it states this on the floorplate.  However, it only has vertical ribs in the body.  I have some pics of the mag, except I don't know how to post them.

Jason, the base plate just says ArmaLite and not Colts' and ArmaLite ??

Is this a waffle-mag ?  Waffle looking design ?

Without the above question answered I saw a similar mag sell for $160.00 but I believe that mag was dual branded.

Will you email me a pic of the mag and if you have it a shot of the floorplate ?

Pic has been emailed to you, 5sub...

Jason, I'm assuming the side of the mag is not in the waffle pattern.

I have three of these mags and they're worth roughly $150.00 - $200.00/each.  Obviously your buyer will be a collector.

There is an old lime-green mag pouch that holds two of these mags that you might be on the look-out for.
I no longer have the link but if you can find the "Buddy Hinton" collection on the net there's some fine pictures.

An even more rare version is the 20-round with the old waffle pattern.

The most rare version is a 15-round ArmaLite mag.  

Your mag appears to be in like-new condition and you've got a Keeper for sure.

Congratulations !!