For the KelTec P3AT (6 rds + 1) that I habitually carry in my right pants pocket, I have a spare 6-round mag of XTP .380 in my left. However, that is only to ensure that I have a clear path to the loaded Taurus PT-145 (10 rds + 1) in the center compartment of my man bag, which has nestled next to it a spare belt carrier with two mags. There are two other loaded spare mags in pockets on the inner portion of the bag. Hence, at any given time when I am out I have immediate access to 13 rds of XTP .380 and somewhat delayed access to 51 rds of .45 XTP. (On trips I throw a 50-round box of each caliber in the bag as refills JIC, and another spare loaded magazine for the KelTec.)
If I'm headed out of town, a folding stock AK and a Mossberg 500 go in the trunk. The AK fits nicely into an M60 barrel bag, with one loaded five rounder in the mag well, and a thirty rounder and a forty rounder in the side pockets of the bag. Next to it, I throw in a Chinese 5 pocket magazine pouch with shoulder strap. Total: 225 rounds 7.62x39 ball. The Mossberg riot gun rests in a soft-side guitar case with a bandoleer/belt made up of a mixture USGI and civilian shotgun pouches (don't believe in open loop Mexican bandido bandoleers since my experiences in the 90s showed that I could never find one that didn't shed rounds while maneuvering like Hansel and Gretal dropping a trail of bread crumbs). Also in the bag is an extra USGI 7-pocket bandoleer containing 5-round boxes of 2.75" 00 buckshot. All told there is something on the order of 110 rounds of 12 Gauge 2.75" and 3" buckshot and slugs (even some birdshot) in the case.
As Bubba said to Forrest Gump, "That's, that's about it."