No having it around your wrist makes you unaccountable for your dogs actions prior to him freacking out. you need to get better at watching and reading your dog. But lets stay on track.

Trust me I know what you are saying with the wrist thing but lets focus and rule outany and all technique issues first before we get in your head and emotions.

So next comment on your technique so far:

With the hand position you described earlier, it seems you are only able to give a one handed correction. The position I am suggesting will give you a better correction evenly and consistantly. Again I will use the example, I bet lots of money that you will probably never see a pro baseball player swing the bat with one hand! Therefore let us not give por corrections in time of need.

Did you say your dog has a formal heel command and does this command in in the auto sit?KOJAK

Yes

Fine, prime the dog and come out of a formal heel.
your dog should sit. YES?
Mind you it is a good note to start reading your dog at this point.
So with that said lets just say you are outside, you notice a distraction and a possible freak out about to happen. With the dog in the heel position and then in the auto sit, and with hands in the proper position, notice the distraction. Now notice the dog taking notice, (before the freakout). Just at that point, take a step straight back just out of site line of your dog. You should still be facing the same way as your dog so you should be just a little behind the dogs right hand side. What you are attempting to do at this point is to sorta sneak away from your dog while he is looking at the distraction.
Now in one smooth movement stepback wards as your two hands correct over or past your left hip pocket give the correction and as you command "no heel". The correction should be given with a speed/force needed to move the dog straight back and off balance. The speed at which you give the correction will bring he dog back to the heel position. The dog will learn to stop watching the distraction and just look at you. From this point pat your leg give the heel command and reposition. If the dog looks away from the distraction praise properly and with purpose not allowing the dog to break out of the work. then go home and call it a day.
And before anyone jumps down my throat, I know this is straight compulsion. But this is not a competition and we are not working drive in this situation. we are working toward the focus on the handler. Your timing is of great importance here and your leash technique is of more importance. Good luck. KOJAK
Always think safty of handler first, then dog and community. This advise has been given based on the understanding that the dog owner has a relationship and history with this dog and a resonable amount of control. It is not recommended for just any old dog.