I think the choice to not have a free floating barrel on the standard model was probably a decision made on durability grounds rather than cost, specifically the ability for the rifle to mount and use bayonets.
Yes, free floating barrel will give you better accuracy, but just how relevant is that difference if you are only planning to operate up to ranges of 400-500m against man sized targets? Even that is probably pushing the envelope in terms of the range PLA general infantry are supposed to engage enemies at, since Chinese infantry doctrine seems to focus more on mechanised infantry tactics where you drive up in your IFVs and only jump out at close range to shoot the enemy in the face at near point blank range with automatic fire to overcome body armour.
Against armour targets, sitting at 400-500m and taking pot shots really are a lot probably game since even if you do hit them, odds are their armour would be able to comfortably stop the rounds and you will be there all day.
American infantry combat tactics (rather USMC) favour such long range engagement because they are facing unarmored targets and have undisputed air dominance. At those ranges, enemy incoming infantry fire is effectively unless against their own armoured infantry in cover, while allowing them to maintain comfortable separation of forces for easy target acquisition and engagement by friendly air assets. The fact that even against unarmored opponents such long range rifle fire against targets in hard cover is unlikely to produce much in the way of enemy casualties is largely irrelevant since the purpose of said rifle fire is to keep the enemy pinned in place for air strikes rather than trying to destroy the enemy outright.