hmmm, I think I figured out why it wouldn't fit.
This is a "Blackhawk" can.
I test fitted the bottom lay with an old mil .50 can. It wasn't an easy fit, but much better than the new Blackhawk can.
I picked up a new Harbor Freight can too, so I tried that. It was just as tight as the Blackhawk, but it's slightly taller than a mil .50 though. Not by much. Probably wont notice unless it's sitting right next to one.
Anyways, I was able to pack 50 into the HF can, but the boxes now have slightly crushed corners or edges. Disappointed in that.
When I look at the length and width, they look exactly the same though. So if it is off, we're talking about 1MM or so, except for the height on the HF. It's probably about 1/4" on that.
Or maybe bc the mil .50 cans are used, they stretch out slightly making it easier to fit.