Your pocket is not the best place to carry extra rounds--at least not if you want to reload quickly. That's why PHs and dangerous-game hunters in Africa keep ammo on their belts, where it's out in the open for quick access. On the trail of dangerous game, a quick reload could literally be the difference between life and death.
Hunters of less-ornery critters can learn a lesson from this, and not just those who like single-shot rifles. Granted, most big game is killed with three shots or less, but everyone I know takes more ammo into the woods with them than their rifles can hold. If you're going to carry extra rounds, why not carry them someplace where you can get to them fast when you need them?
I learned the value of the Galco Gunleather Safari Five cartridge wallet while honing my rifle skills at Gunsite before going on safari for Cape buffalo. Plucking cartridges from the wallet, I could reload my rifle without taking my eyes off the target. Luckily I didn't need a reload in Namibia, but having five rounds riding on my belt in the wallet brought (some) peace of mind as my PH and I stalked into a herd of buffalo.
I liked the convenience of having additional cartridges within easy reach, so I started using the Safari Five wallet while hunting other animals like deer, black bear and aoudad. The wallet keeps rounds organized and quiet. Although it's made to securely hold large, long cartridges like the .338 Win. Mag. and .416 Rem. Mag., it works just fine with smaller, shorter stuff in the .270 Win. to 7mm Rem. Mag. class. Plus, the wallet's premium, hand-stitched leather with brass hardware just looks classy.