Sturdy, convenient - MTM Case-Gard 50 Rifle Ammo Boxes .22-250 to .308 Green RM-50-10

Every reloader probably has dozens of these. I've never had one break or come open in my range bag. The newer mechanical hinge ones are a little bulkier than the old flexible plastic, but you no longer have to fight with them trying to close themselves on the range bench. Great price, made in the USA unlike other brands that cost the same.