You can clearly see the seam where the mandible bio helmet attached to the face.
Due to how Casting works though, theres likely always going to be a seam
hm. that exact seam is not there because of casting. i hope a little story of HT predators will be interesting for anybody who doesn't know it
first they sculpted mandibles separately just to have access to sculpt the inner mouth properly. mandibles then were glued to the face. there is no way to sculpt the inner mouth well with outer mouth closed, see? every one of four mandibles is glued separately.
then i guess they decided to hide a seam behind a wide predator cheek or just make bigger parts and not lose them at factories.
then they decided that it's possible to make a double set of mandibles. they stopped glueing mandibles to the face for that purpose. it was their first P2 - battle damaged version. he now had replaceable mandibles, like all other predators have today (except for the faceless ones).
then they decided to sculpt an entire lower faced glued to the helmet.
so now it is a set of 3 variants - closed mouth, opened mouth, mask, plus the lower jaw is removable to be replaced with a mask attachment.
so that exact seam, which is actually a rift, was always practical, and what it proves in my mind is that this jajuja has a face under that mask.
falconer/tracker heads don't count! they are a 100% cast from a berserker head, which had space for a replaceable mouth.
there is no reason even for tsang to sculpt the head in two pieces if there is no need for it.
especially for tsang, who hates separate details like they did something to him in his childhood.