The myth is that ant chain mail armor or mideval armor can deflect a bullet with on ly small injurys to the wearer

Obviously untrue. It couldn't even stop an arrow, why would it be effective against a bullet?

The question here is: Which armour? Which calibre bullet? Blackpowder or smokeless? Centre-fire late 19th century rifle or English Civil War flintlock pistol? Full 16th century plate tournament harness or medium length maille byrnie from the 11th century?
Because the way you've phrased the question the only possible answer is a definite "Maybe".