If you can pull the bolt out til it stops, turn the BCG upside down and place the bolt face on your table and the bolt does not slide in, your gas rings are likely OK. If the bolt slides into the BCG on its own or at the slightest touch, then you need new gas rings.

How many rounds has the BCG seen?
If you hand cycle the rounds does the bolt close properly?
is this a new build?
Can you post pics of the wear you have observed?