Unsure believe it's just loose ammo.Thanks for the useful data, but it would seem some of those figures are for boxed ammo, and some for loose. I may be wrong, but it would be nice to know which is which.
I base this on personal experience, knowing that you can easily fit 2k rounds of 855 (5.56) on stripper clips, into a .50 cal can, if they're not in the cardboard 30 rd sleeves.
The .22lr in .30 cal boxes is loose.