Yeah, so I made a base state machine that goes from a weapon holding Idle/walk/run state, to a weapon aiming state, without an aim in / aim out transition between them:
and also made a transition state machine, with the aim in/out states included: (these aim in/out transitions are the full body animations, not just upper body)
Then I had to do some funky blending, I blended the transitions state machine with the base SM as upper body / lower body, which would result in a upper body only transition SM, and then blended it again with the full body transition SM, this time by bool, if the character is moving.
that worked fine (in theory), it would use the aim in/out legs animation if the character was stopped, and the locomotion legs if character was moving, and blend between those in real time as it started or stopped moving as the transitions were playing.
the problem is that when blending a state with itself, it was kinda breaking the regular IWR for some reason, exaggerating the animations as if it was being added on top of the other (it wasn’t.)
so I had to add another blend by bool to use just the base SM without the transitions, if the character was empty handed. that fixed everything that I could notice, so far at least. 
now I got a new, different problem with light hit react montages, but I guess I should open a new thread for that