After a few years of waiting I finally pulled the plug on my 6.8 SPC PDW. It is a Mini with a 10" barrel. The form 1 to SBR it has been submitted. My 16" barrel XCR 6.8 had the original tube stock which I liked but I have since installed the new FAST stock on it which I also like. When I get the stamp back do I install the tube stock or the FAST stock on my mini?