Generally gun dogs are divided into three major classifications: retrievers, flushing spaniels, and pointing breeds.
As a result, retriever breeds are bred for soft mouths and a great willingness to please, learn, and obey.
"Hard mouth" is a serious fault in a hunting dog and is very difficult to correct.
A hard-mouthed dog renders game unpresentable or at worst inedible.
[1] To carry out the duties of a gun dog, a retriever should be trained to perform these tasks: Although most individual retrievers have the raw capacity to be trained to perform as a gun dog, a significant amount of thought and effort is given to breeding in specific desired traits into dogs from field bred lines that greatly enhance the training process.