Is My Puppy a Full Blooded Pit Bull?

I just got my Pit about a month ago; he's 6 weeks old. I bottle feed him, etc. The previous owner told me his mom was a full blooded rednose and his dad was a rednose and bluenose mix. He has high muscle definition in his upper shoulders when playing and high muscle definition in his back legs. The only problem is I don't know if he is truly full blooded. Any ideas? I paid $50 for him. And if y'all do know could y'all possibly tell me what kind of Pit he may be.