Breech O Rings

I changed my Breech o rings on my Condor after i noticed a white vapor coming from the Breech area ,sometimes I would just get a low power shot.
Removed the original o rings and installed 2 A011 7.65×1.78 Vitons from a Harbor Freight kit cleaned and reassembled the gun and checked function of Breech when cocking gun it seemed to slide and click on Tophat when closed, shot the gun afterwards but it seems louder than before is this normal or will I have to replace them using different O rings? Thank You.Tony.