I would look thru the previous post on the DDB and send private messages to the people who breed or have good DDB and look at dogs with a longer more functional mouth there were three types of DDB the show breeders are usually just breeding the under shot jaw to the extreme you can still find the other types in the same litters just some of the breeders might consider them not breeding stock because they aren't extreme and different and more functional the old pictures don't usually show a extremely undershot jaw because it has no value in a working dog some can work around there structural show flaws with heart but why breed a flaw.