Originally Posted by fragout
According to the reviews about the Doublestar, the lower receiver and bbl are marked 5.56mm.
If a firearm doesn't have iron sights, then I wont own it. In this case, I'll be using a GGnG MAD flip up rear sight.
I was pretty sure that most of their stuff was 5.56. J & T, is the same company as Doublestar, except that you can buy the same gun in a "KIT" and pick what options you want and assemble it yourself. You would have to buy a lower receiver, but then you control QC on how it all goes together J&T 16" DS-4 Kit
And most of the complete AR's you see out there now, normally sell without the BUIS. Mainly because that is one of the areas that people are picky about, what type of sights or optics they will be using.