Honestly the M16A4's extended mag variant makes the mag look like a 7.62x39 with it's curve, even though it is a 5.56. Maybe show less of a curve?
7.62x39 (What ak's use.)
5.56 Stanag Mag
The M16A4 uses the Stanag.
Sorry if this annoys you, but it does annoy me, it's just what I noticed when looking at it. So unless you want an ak to shoot faster 5.56 and an m16 to shoot giant ass 7.62, go for it.
Actually, it just looks like the top of the M16's mag is at the bottom of the Mag well :P
No offense, but some crappy airsoft gun makers do it better