As GQhoon said, have you seen the parents working? I think if you had, you may reconsider one as a deer dog.
I would say if deer is your main species you hunt then a brittany probably isn't the best choice. Even if you do screw it down enough for deer, neither man nor beast will be happy with the arrangement. You will be forever hacking him back in, he will forever wanting to range out like they are bred to do, and do well.
Do I place faith in trials results? Depends on the trials. NZ pigeon trial? No. Australian trials where they shoot birds over the dog and retrieve on the spot? Absolutely
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