I grabbed a number of these bags back in the day.
Big center pocket, with a velcro flap on either side, and six pockets big enough for two BAR mags, and a handy (if skinny) shoulder strap. Nice rigid bottom, too. Price was right, around $10-15. Only add-ons are the paracord on the zipper and the IFAK on the shoulder strap
Wasn't really looking, but was at a gun show (Fort Worth, if memory serves) and saw this one in Navy "blueberries" camo, and dropped the $20 the vendor wanted for it.
A bit bigger, handy for rifle stuff (long enough to stash an uncased spotting scope & tripod; enough pockets for every random thing you'd want on a bench. Decent shoulder strap, too. Only the three "magazine" pockets, and a bigger, single pocket on the opposite side. This one also has an IFAK on board. (It's really blue, I swear, phone camera color correction is wobbly out of full sunlight.)
The "six pocket magazine carriers" are available, off and on, from the online surplus places, for about $25. The bigger bag is now $30 from the dude who works the Premier gun shows.