My workflow - highpoly moi3d + fusion360, then uv mapping + lowpoly in Maya, then Substance Painter for texturing.

Not sure if anybody is interested, but I'd like to give my models for this community to take a look, maybe somebody can point me out some mistakes or it will help another way.
But please keep it just for yourself, not to spread it to another persons outside this forum. 3dm + fbx UV mapped lowpoly

www.b-east.cz/work/weapon_moi3d.zip

Vojtěch