I'd bought a not-too-thin nylon bag with a drawstring top at a yard sale
for nawthin ($1?) on general principle. Then I realized that I was
starting to pile up 10-round PMAGs on the one shelf in our safe;
and that the proper time to load them was before something needed shooting.
So I stacked the (now loaded) PMAGs very neatly in the bag,
and it's hanging on the door of our safe.
If I had to take the AR'n'ammo elsewhere,
I'd put the sack into a backpack.
(And I'd look mighty stupid having to dig into a pack
in order to reload).
But its primary purpose to to move the mags from
the Ready Ammo Locker to whatever place on the property I need it.
If I need the ammo around the house, I'm not gonna be standing around
the citadel shrugging into some tacticool load-bearing vest before moving out.
I probably ought to store one of the spare earmuffs C-style
around the sack - they'd sit there just fine...