I am looking at throwing a systema bore up kit into my zombie killer, just because it's laying around. That being said, should I downgrade the gearbox so it doesn't crack or should I leave the spring alone? I was thinking downgrade and then put a 6.03 or a 6.01 into it. then of course a suppressor to hide it all. I haven't decided, any advice bros?
EDIT: Don't say return it, I already tried and it was a no go. Evike sent me a brand new one, I already asked for store credit.