Quote Originally Posted by Guns4Fun View Post
A RLL and a RDIAS will only work in an AR lower.

Heck, even some of the newer AR lowers need to be modified to allow them to work. You'd need to mill the lower to get either of them to work with a Colt lower. I'm sure there are a few others that have a high shelf.
My lower is drop in ready. Not like I have 7,000 to throw into a rifle anyway LOL.