Comparison of the handguard distal end between QBU191 and QBZ191.
I can't see any connection between the HG and the barrel on the QBU like we do on the QBZ, so I'm tempted to say this is the best confirmation we have yet that the QBU191 is indeed free floated.
It seems QBZ-191 use LMT style 1-piece piston instead of H&K 2-piece piston. It seems you could remove the piston from the front of gas block after removing the gas selector without removing the handguard like in HK416.