I have 3 of those cases. Each is loaded with a minimum of 1000 9mm, 45acp or 40 caliber. Two of them have around 1500 rounds and I've had no issue with them other than the potential Hernia from lifting one.
Those are the old style or the new? The new ones have a very different design and are slightly larger, which sounded good until I moved all my 9mm to one and had the handle break free and drop 80 pounds of ammo on my foot. Really lucky that I didn't break anything, but it was bruised and swollen for a week or so...
You can see where the plastic in the new design simple stretched and let the handle release on one side. To be fair, they do say right on the label not to load them to more than 35 lbs, but I never had any problems with the original design.