The Unimag is available through Primary Arms

[aerostar]

http://www.primaryarms.com/rze-mag-001b/p/rze-mag-001b/

 

[MErl]

And what exactly is a unimag? (other than something that is not allowed in CO)

$40 for an AR mag that claims:

Capacities with various calibers listed below
.223 Rem / 5.56 NATO / .300 BLK / .204 Ruger / (All .223 Parent Case) 30 rounds
5.45x39mm 29 rounds
6.8 SPC 26 rounds
7.62x39mm 25 rounds
6.5 Grendel 24 rounds
.458 SOCOM 12 rounds

 

[Arizona_Mike]

It's more about feeding reliably and OAL than capacity IMHO. In fact, while I love 30rd 5.56 mags (except I'll usually have very light aluminum D&H 10-rounders when I hunt), I'd rather see a shorter .300 BLK or .458 SOCOM mag myself.

Mike

 

[MechAg94]

IMO, 20 round mags or smaller are ideal for range use (or most uses that don't involve combat or self defense).