
I have a 14wks old pup.. he is the worst nipper I have ever had ..some puppies can be worse than others.
The 'ouch' also with him seems to fire him up so I do not use this anymore, I use the off and ignore method and also find if I stop dead in my tracks if he is after my feet or has a grip on my hands ..he will let go..I actually picked this up from one of my older bitches I noticed when he jumped at her and grabbed she stood completely still and looked away from him he would let go and walk off, most of the time the dogs know how to deal with situations with pups better than us :).
I also had a chat to a friend who is a brilliant behaviourist, he gave me a little task to try out on him which seems to have worked very well.
Its hard to explain really but here goes.. in one hand have some smelly tasty treats put one inbetween the fingers so he can see it slightly and smell it which will encourage him to try to take it ,put your hand into a tight fist, in the other hand have just one treat sit him in front of you and let him mouth the hand when you say 'no' the moment he stops and looks at you open the other hand and give the treat. You have to be spot on with the timing.
You also have to make sure when you give a toy to stop the biting that its not looking to him as a reward for the behaviour.. you need to be able to see just before the nipping begins ( I can see the change in the eye) and replace your hand with the toy ..once he has nipped ignore him walk out the room for a minute or two if it is safe to do so, then return and ignore.
I also agree that the behaviour is worse when its nearing time for a sleep so I have more of a timetable which I try to adhere to so that he gets plenty of rest ..I also do little bits of training and some ringcraft at some point during the day not forgetting his little walk to release some of the energy, which has been really difficult with this awful rain.