http://www.voodootactical.net/molle-gear/padded-weapons-cases.html
In my first Voodoo I can fit either one of my LAR-8 rifles, 30 loaded 20-round magazines, plus my Mossberg 930 SPX and over 100 rounds of buckshot and slugs. That's how I load it out. Usually. Due to the mounting systems inside the case, with a little ingenuity, you can fit a ton of smaller stuff.
It came with a single shoulder strap (more than capable of sustaining that weight for extended periods of time), backpack straps, a dozen or more pockets that will fit .308 Win. sized mags and other stuff, heavy duty zippers: not the crappy thin gauge zippers that pull apart under the slightest strain.
MOLLE system and D-rings further enhance your options.
While the Voodoo cases retail for over $100, I got all of mine (and one of 98's) on sale for like $70 at Sportsman's Warehouse. Similar deals can be had elsewhere.