I am sure PLA regulars use the Type 03 as well, maybe the paras?
The PLA is very big on laying good foundations in their training.
One of the basic exercises they love to do is to get their troops to hold their weapons absolutely still in shooting positions over extended periods (up to several hours at a time).
To ensure the weapons don't drift, the instructors would balance a round on the barrel of each gun, so if the barrel wonders, the round drops to the ground and the recruit would have failed that exercise.
This could be a basic version of that exercise, where the recruits are just being taught the correct postures they need to hold.
If they were anywhere close to line troop standards, I would expect them to be holding their weapons crouched or even standing, not in the easy prone position with bipod assist.
In addition, PLA regulars always displace good trigger discipline, so that is an immediate give away that these are not out of boot camp.