0000 buck, and 4 buck each deliver devistating amounts of lethality, with a higher pellet count than 00Buck. Just remember that all 3 easily penetrate mulitple walls of a house or apartment, if you are thinking of using them for a home protection gun. Pellets missing the perps could endanger your own family ora neighbor.
We always used low brass 7 1/2's in a 20ga Ithaca mod 37 pump for a defense gun here, in a typical home defense shooting of 7 feet to 7 yards, it is still a very tight group, & anyone hit in the chest by a 7/8oz load at those distances is going to fold very easily.
I don't know long the Norinco 97 will hold up to full power buckshot loads, but the original Win 97, could digest thousands of em & still be fine, especially the take down version where the headspace could esily be adjusted.
be safe, enjoy life, journey well
OFC, Mo. Chapter