I have a few Colt 20rd mags in like new condition. How do I tell which are more valuable? Which are from the 70s and why are they better? What do these mags go for?

Of the few I have some have the following similarities & differences;

Some of the mags have a slot (about 1cm) cut on the right side on the opposite side for the mag catch slot and others dont.

Some mags have what looks like a "C"  or a "I" on the front and one doesnt.

Some say 5.56 on the floor plate and some say .223

All of them have Colt floor plates. One of them is silver the others are black.

All the followers are a dark metal

Quoted: I have a few Colt 20rd mags in like new condition. How do I tell which are more valuable? Which are from the 70s and why are they better? What do these mags go for? Check the tacked mag faq thread at the top of this forum for dates and markings.  Check the equpment exchange here for going rate. Of the few I have some have the following similarities & differences; Some of the mags have a slot (about 1cm) cut on the right side on the opposite side for the mag catch slot and others dont. Sounds to me like they were bubba-ized to fit an AR180- certainly not original. Some mags have what looks like a "C"  or a "U" on the front and one doesnt. All of them have Colt floor plates. One of them is silver the others are black. All the followers are a dark metal

the faq thread at top doesnt discuss the COlt 20s
this is a specific comparison of a brand of mag

Try here (I thought it was still tacked)...

magfaq.tripod.com/

The silver floor plates are just a variation- certainly more rare than the black.

Look for a small "1-in-circle" near the bottom of them which means they originally shipped with SP1 rifle.

GoGo

It looks like the ones marked 223 are from the 60-70s
does this make them more valuable?
all of them have metal followers