The mags WERE detachable, but not a box they were the large scale rotating assembly you see above.

Fun fact, the mags themselves were fed by 25 round stripper clips.
2
0
3
Omg now I have to have one
0
0
2
My point still stands. Box mags are infinity better.
1
0
1
The point also highlights an issue the field testing bumped into:

They only made enough mags for one per machine gun during the field trials, which implies they couldn’t easily make more as you would have wanted multiple for such testing in most cases. The mags were cool but VERY complex to make.
0
0
0