Quote Originally Posted by ESnel View Post
There are a number of companies that manufacture a proprietary upper/lower that use a large number of AR parts but don't fit AR uppers/lowers. The Stag 10 is an example of this as to the number of DPMS 308 AR parts it uses but is not considered a 308 AR or variant.
You can fit at least one upper that is supplied with a restricted rifle, to the Stag 10 lower.