5.56 NATO vs .223 Remington

[MT2008]

Originally Posted by Gunmaster45

I also shot the two HBAR A2s. One I realized has no magazine fencing on the lower, but it was clearly marked AR-15 A2 Sporter HBAR, so I wonder if magazine fencing isn't the best ID of an SP1 lower...

I'm pretty sure all of the original AR-15 A2s (regular and HBAR) had the exact same lower receiver as the Sporter I and Sporter II. I don't think Colt started selling them with the fencing around the mag release until around 1990. At least, that's the impression I get from looking at my Dad's old Gun Digest issues.