Ammo Another possible CS frag?

[J.H. Moose]

I probably should've posted this alongside the Read I shared earlier, but this one I'm not as definitive about. Found in the same bucket, definitely looks like a base frag. The even shape makes me think a polygonal cavity type Read, although it could be something else. A Read sabot fragment I have fits conveniently well along the lip of this frag, what do y'all think?