Out of curiosity, In rifle barrels was the CCI SV target 'subsonic'. As you stated for high volume use the lead outside wax lubricated bullets will require cleaning at a lower round count in a blow back rifle.
Some of the 50 yard .22 bench rest rifle people say they never clean their rifles. They ammo that they shoot from what I have seen often has either wax or a grease on the bullets. The guns are bolt actions and so a tight chamber is more readily fed a round.