After doing a lot of internet searching and a few phone calls I want to share some information I found out about some of the receivers.
Paragon Manufacturing (a five star Company) has been providing superior service and quality machined parts for multiple industries including aerospace and defense. Century Arms contracted Paragon to make their VZ2008 receivers. For the VZ2008 receivers they Start with the best possible grade of steel (4140) and properly heat treat. On both of my rifles the machining looks to be top notch. After searching the internet, I have never read one bad review about the VZ2008 receiver.