Rem-umc 223

This may have been shown on another thread but my search doesn


Very interesting.

That’s not a Rem commercial load but one of the pre-NATO experimentals tested during the development of the Armalite rifle. That would be the 3rd headstamp used. The first was “222”, the second was “222 SPL” and the last was “223”. But you probably already knew that.

I have one that has the base painted a very light red or pink but no color on the bullet. Another has the same light base color and a standard red tip which I suppose is simply a tracer. Another is a blackened case dummy with a pierced primer.

The color must mean some sort of special loading but I have no idea what it is. Tracer? Proof? Special bullet?

I hope someone can answer. Maybe Daniel Watters is reading this and can tell us.

Do you have any dupes?



Thanks for the input.
Would these two cartridges be part of the same testing program?

Sorry, no dups. I only have 1 of each.



Yes, it was the final testing of the Armalite design with cartridges made by Remington. The Winchester rifle submittal was chambered for their cartridge, the 224 Winchester, which was practically identical to the 223 Rem.

For whatever reasons, the Big W had a hard time meeting all of the requirements and changed their cartridge at least 5 times. Maybe the tests were rigged in Armalite and Remington’s favor???


I knew I remembered seeing reference to this cartridge somewhere!
David Hughes makes mention of this same cartridge on page 105 of his History & Development of the M16 Rifle & it’s Cartridge together with a colour photo. Hughes states that this round was once believed to be a tracer however x-rays have subsequently proved it to be a ball loading. I know this doesn’t explain why it’s marked in this way but it does at least confirm that this is a genuine - and very desirable - cartridge.