Blue pits and bullies question

I do own a blue pit but I do not believe that blue has always been in the gene pool. Example for years I raised champion blood labradors then I swapped to weimaraners. Once upon a time I breed a Weimaraner to a chocolate lab had blue pups. Kept a pup and bred back to a brown lab. Basically ended up with blue labs. Well now the akc recognizes "silver labs". And you can tell by most that they have Weimaraner in them if you have been around both breeds. All you would have to do is have two papers labs and breed a Weimaraner instead of one of the labs but use the labs papers keep a pup and do again. I giggled the first time I saw a registered silver lab a buddy bought for a grand and it had thin floppy ears like a Weimaraner. I never registered and sold but there is no doubt in my mind that's what somebody did labs have been around to long for blue to start popping up. Just like pits someone bred a different dog probably a Weimaraner and was using a registered dogs papers. Kind of like I have also seen Merle pits. They did the same thing but used a catahoula. Just because a dog is registered does not mean anything when somebody is in it for the money this I just my opinion.