Let me preface this post by saying I can close a #2(per IronMinds regs) and have closed a #2.5(per IronMind regs, almost back to doing it again).
I noticed some folks stating that they don't feel like all the muscle groups of their hand/forearms are getting a work out using the CoC. Thats cause of a simple fact of leverage. Same principle behind when you use a cheater bar to break a bolt loose as your pushing down or up on the END of the extended bar. With the spring up your pinky and ring finger able to use the most leverage provided by the handles thus working those two fingers. With the spring in the DOWN posistion the index and social finger are now taking advantage of the leverage provided by the handles. So by doing sets of both up and down your getting a full grip work out.
Here is how my CoC workout goes:
3 sets of 10 with the spring UP each hand, one minute rest after each set
3 sets of 10 with the spring DOWN each hand, one minute rest after each set
Take a 10 minute break
3 sets of burn outs(close the grip and squeeze till you fail) with the spring UP in each hand, one minute rest after each set
3 sets of burn outs(close the grip and squeeze till you fail) with the spring DOWN in each hand, one minute rest after each set
Trust me this work out is going to suck big time. But you will see improvements.
Oh and if you didn't notice, I don't do warm up sets.