Hitting all six

Hitting all six
 

I was watching Boardwalk Empire and heard this dialog:

Jimmy Darmody - Doc says you're doing good.
Pearl - Does he?
JD - But you gotta leave it alone.
P - It itches!
JD - That's good. It means it's healing.
P - Did your leg itch in the hospital?
JD - For a while.
P - But not anymore?
JD - No. Now it's hitting all six.

I understand it is something like full-gear or "the most of it". Am I wrong? What's its origin? the lottery? Thanks.

You are right about full gear---all six cylanders. It may be that in the 1930's six cylander cars may have been the type gangsters drove. You know, Pachards and Cadillacs.

I think this must be the origin of the expression. There is a similar British one - firing on all cylinders.

Thank you very much Poli and Perikles. It looked like an idiom to me, but I couldn't find it in the many dictionaries on-line and just found a few dozen instances using Google. Maybe it's a bit outdated expression and that wouldn't surprise me as Boardwalk Empire makes an obsessive reconstruction of the '20s, including language, that is commendable.

If it is an idiom and it was "unattended", well, mission accomplished because I just looked it up again and this forum thread is hit number 1 for "hitting all six" -including quotes- and 1 to 4 without quotes. :)

Well, that was bothering me too, so I look on google but search something more and found out one really good page for Boardwalk empire.
On that page there is explanation:
Hit on all sixes - to perform 100 per cent; as "hitting on all six cyclinders"