I carry my spare Glock mags in a model CO-157EP. I carry mid-size G23 mags, but full-size G22 version will also fit. The little Baby Glock mags get lost in this pouch but do fit well in the pouch detailed below. Also there is enough wiggle room that I think the larger .45/10mm Glock mags will also fit the 157EP.
http://www.ripoffs.com/datasheets/co157/co157.html" onclick="window.open(this.href);return false;
Some photos of my Glock mag in this holster:
http://i850.photobucket.com/albums/ab70 ... a9c3e1.jpg" onclick="window.open(this.href);return false;
http://i850.photobucket.com/albums/ab70 ... cfa0ef.jpg" onclick="window.open(this.href);return false;
http://i850.photobucket.com/albums/ab70 ... e7a03c.jpg" onclick="window.open(this.href);return false;
http://i850.photobucket.com/albums/ab70 ... e9ac63.jpg" onclick="window.open(this.href);return false;
As you can see in the photos, the mid-size Glock mag just disappears in the hoslter, totally concealed but still easy to draw.
When carrying my S&W J-frame revolver, I keep spare ammo on a pair of Bianchi Speed Strips carried in a Ripoffs CO-184EP (this holster also works for Baby Glock mags - though I usually just carry a mid-size Glock mag as above as spare for my Baby Glock).
http://www.ripoffs.com/datasheets/co184/co184.html" onclick="window.open(this.href);return false;
Some photos of my speed strips with .38 +P ammo in this holster:
http://i850.photobucket.com/albums/ab70 ... bdafa9.jpg" onclick="window.open(this.href);return false;
http://i850.photobucket.com/albums/ab70 ... de9ac5.jpg" onclick="window.open(this.href);return false;
http://i850.photobucket.com/albums/ab70 ... b40342.jpg" onclick="window.open(this.href);return false;
Here are both holsters next to a Ripoffs CO52 (in the middle), which I use to carry my iPhone wrapped in an OtterBox protective casing. Because the OtterBox is so large, the phone won't fit in standard iPhone holsters. This CO52 was original designed for some old PDA (Ipaq, I think).
When carrying one or the other spare ammo pouch, it looks to the casual observer like I just have two cell phones or a cell phone and a pager (not uncommon in a tech-savvy town like Austin). With my Glock tucked in a Crossbreed SuperTuck or my J-frame in a pocket holster, I feel very well concealed.
I also carry my Ruger LCP and Walther PPS backup mags similarly, but haven't found the right Ripoffs for them yet. Instead I use small camera pouches that secure to my belt with velcro belt loops. The LCP mags are in a Tamrac model and the PPS mags are in a Lowepro model (don't remember model numbers off top of my head).