I want some opinions to back my position (I'll tell you later) in an argument with my 18-year old stepson.

Our disagreement is this:

My lab's biggest weakness has always been that he breaks when he sees a bird fall, even if he is in "stay" mode. I need to break him of this. (It doesn't really affect his ability to retrieve, but means I can't duck hunt out of a boat with him).

The two scenarios are this:

One of us thinks the quickest way to breaak this habit is to use a German-style pinch collar, pulling back slightly when he starts to break.
The other says hitting the dog in the face with a cap everytime he starts to break is the more humane method- pinch collars are cruel.

What are the opinions here?

To settle the argument I would use the pinch collar. Pinch collars with the points filed off are humane. Second, if you are hitting your dog with a hat your dog will associate your hand which holds the hat a threat. This could lead to other problems ie retrives to hand.
Personally I would work the dog in the yard with the pinch collar or better yet an e-collar if you know how to use one. Then if the dog breaks before you command him on the fetch you can let him know who gives the directions come hunting season,

Suggestions:
1. Follow a proven sequential training program
2. Pinch collar is better than a cap in the face (but #1 is where you need to start)

I would start from the beginning and re-establish sit. I would put a check cord on his callar and sit him and a mat or board, command sit/stay (I don't use stay because it is redundant) and pull on the check cord. When he leaves the board, correct him, and put him back on the board. Do this until you can throw a clip wing pigeon in front of him.

Dr Fatguy

Of the 2 options you provided I would use the pinch collar. Now I have mostly dealt with Pointing dogs but what I have seen used for a dog that brakes point to go after the bird is the keep a check cord on the dog and plant a bird in a launcher and let the dog find the bird the dog goes on point and he release the bird and allow it to take flight, if you have two guys doing it one can shoot the bird as the other keeps a firm hand on the check cord and allow the dog to do as it wishes if it takes off after the bird hold the check cord tight and allow the dog to give himself the correction when he gets to the end of the line. Mix this in with letting the dog get the retrieve on command and it seems to work pretty well.

Also I have read you can place the dog in a sit/stay and throw the dummy sometimes let the dog get it some times you walk out and go get it. praise when the dog follows the command and this is suppose to keep the dog guessing as to which action will get him the praise. It is also supposed to teach the dog that not every retrieve is his only the ones you tell him to get.

I would also say the pinch collar. But do not pull back on it. Allow the Lab to pinch itself. Only release it when you are satisfied with the hold.

This can cause problems as well. At least with my spaniel. She would do the same. But the biggest problem was, after the pinch collar. She would squat in the rears like she wanted to sit. It took a lot of work to get the point acrossed to her but it was worth it.

I use a pinch collar and about a 15' rope.
1st I tie one end of the rope to me around my waist. Then I run the other end though the collar and hold that end in my hand (make sure the end you are holding does not have a knot in it) I make sure the dog and me are clear of the rope so we don't get tangled up. Now Have some one throw the bumper if the dog breaks don't let the end of the rope go and the dog will hit the end and not like it have the thrower pick up the bumper and repeat the steps until the dog doesn't break. once the dog stays steady after the throw let the go of the rope and send the dog on the mark as the reward for being steady.

I don't see any pros of hitting the dog in the face with a hat.

Thanks to all for confiming what I was pretty sure of already. I just can't convince him that hitting a dog you are training does NOTHING to establish a trusting relationship. A good retriever should retrieve because he wants to please you- not because he is scared of the consequences of not doing so.