HI Chris . The noise you hear from the hammer is loud as its next to your ear , and i must say that the baloon idea isnt one ive not heard or would try for that matter . You say - Guide rod ( steel), Striker/hammer, Main Spring (standard), Guide washer and finally a spacer washer. The best thing to do , to reduce noise is polish the metal faces that make contact . OR you could look at the possibility of using a PTFE washer to dampen the sound . You would have to turn it down a bit though if you were to go down this road , but as i know its something that rapid shooters do i can say the differ