I carry one extra for every gun i carry, unless i'm carrying both handguns at one. In that case only one extra for my 945 and my P-64 gets to be my BUG. Don't really need another mag for that if i get down to the 9mm, i need to make a speedy retreat.
WOW! Do you all live in Detroit? Most of the time my only carry weapon is a Double D with 2 rounds of buckshot. If I am going some place scarry I'll pack one of my .45s. Spare Mags or ammo, it's in my saddle bags or in the cage somewhere. Although I recently bought a sholder rig that carrys 2 spare mags on the off side, I tried this with the spare mags and it did help ballance the rig out but I still don't like the sholder rig unless I'm wearing a jacket.
To the average non gun carrying person, I could see how it looks as though we are carrying a lot of ammo. My contention is that if the SHTF ever happens, I want to be prepared. I am sure you all feel the same.
Two extra mags for the PT1911, so 25 rds total. Found a cheap dual carrier in a guy's "junk" bin at a show last year for $5, and although it probably wasn't made for mags it works perfectly. A lot of generic folding knife sheaths can be had for cheap at shows as well, and they can work also.
When I used to carry a single mag in my pocket, I cut up an old piece of denim, wrapped it around the mag (about 3/4 length), and sewed it along the side. Sort of like a magazine condom; just something to keep the dust out.