Cadre fire a 3mm discarding sabot penetrator from their powered armor's attached battle rifle. After her escape from Soisson's, Alicia cut an internal brace from her ammo tank to add an extra 40 rounds of the linkless belted 5mm caseless.
1) If it's linkless, how is it still "belted" ammo?
2) Unless the upper brace Alicia cut away was totally unnecessary in the first place, how it it only 40 extra rounds of 5mm rounds instead of say 100?
5mm is pretty tiny, and from the description in text:
Now she doubled the linkless belt neatly and cheated the last few centimeters into place with an adroit twist of the wrist and a peculiar little lifting motion that slid it up into the void created by a few minutes' work with a cutting torch.
"See? That upper brace is structurally redundant; taking it out makes room for another forty rounds—as we've told the design people for years."
40 rounds of 5mm caseless would be 200mm length, doubled would be only 100mm length by 10mm wide. Which is really damn tiny size for a structural brace. Not to mention an absolutely ridiculous shallow angle which couldn't possibly brace anything.
My math is probably horribly wrong, but a 100mm base/height, with a brace angle of ~45 degrees for good structural strength would be ~141mm long brace. Area of this braced triangle would be ~5000mm, or approximately 100 rounds rather than merely 40.