I am not so concerned with you changing the jam % or cooldown, do this however you feel is needed for balance, but there is one thing which is very important to change:
Make sure the chance to jam, regardless of the % only applies to 2nd firing within one cool down.
Right now, the change to jam applies to every shot, including the very first one. It should only have a chance to jam if you fire it twice (or double tap as some put it).
Edited by Elddar, 15 December 2013 - 01:40 PM.