I have run a fair bit of Warsaw pact laquered steel cased 7.62x39mm, from various surplus suppliers, it seems to work well enough in that department.
However my batches of 7.62x54R Warsaw pact surplus has always been a basic steel case with copper wash, it too worked well, being former front line ammunition.
Now this steel cased .303 stuff could be a very different animal regardless of who is making it.
I know that Chinese ammunition in general is a common item in Canada and the reports are in my opinion, mixed. Some users are simply cheap, and looking for cheap ammo to throw down range, other more diligent users has reported some very serious QC issues with the bulk amounts of new produced 5.56mm. Some projectiles were running well undersized in the same lots and performing as you would expect.
Although it can be difficult to track the path of production in this world market of manufacturer-middleman-middleman-middleman-retailer-customer if we could figure out exactly who is building the ammo and their clients it would be a good place to start. If I find any of it, I will do a teardown and post my findings. However currently I have not heard or seen of this steel cased .303 ammo aside my readings here.