I shoot pins alot and I want to start using my wheelgun for this. However, After about 30 rounds of DA, my trigger finger gets really tired and my groups start going all over.
I'd like to find an excerciser (like a grip ball) but made for my trigger finger. The type I'm thinking of uses springs for resistance. I haven't had any luck looking so far. Anyone got a source for this product? I know I've seen them for sale at fun shows.

Edited to add:
 I want to use this at work and while driving so just using the revolver isn't an option.

i have a product called the "gripmaster" which was orignally developed as a training aid for rock climbers. it is capable of excercising all fingers, but could be used for just the trigger finger.

maybe try a web search or local outdoor store?

I have one and I got it from Eastern Mountain Sports.  They are on line at    www.ems.com  

And have a store  in VA    

Arlington
The Market Common
2800 Claredon Blvd. Suite R550
Arlington, VA 22201
703-248-8310


I just checked and they have the IMC Grip Master for $14.00 on their web site.  It is listed under Climbing Gear  Training Equipment.  I have one and I like it, the part that goes against your palm is shaped like the back of an auto pistol grip so should work just fine for what you want it for, good luck and enjoy.    

VINCE AUT MORIRE (Conquer or Die)