Re: ar15 lower reciver which one
We are a "manufacturer" according to the ATF which in reality doesn't mean much. We do just like what most big name manufacturers do and use other people's parts, because in reality, ther are very few actual manufacturer's out there who make all of their own parts. If you ever go somewhere like FN in South Carolina you will see they are making parts for HK. At the same time they don't make all of the parts for their own rifles.
That being said, not all parts (even mil spec) are the same. We use a lot of Rock River receivers and have great luck with tight fits. We also use a lot of Delton and Armalite and I actually prefer the Delton. I have also tried out Palmetto State Armory with horrible results. Plus crazy as someone jokingly suggested does not claim to be mil spec and I wouldn't assemble a kids toy gun with one. We have had some Spike's on order for a few months, but have yet to see them so I can't speak on them... Stag is ok, but I won't build precision builds with them. Any of the billet receivers bgbmboo recommended are good,though I haven't mated a billet lower with a forged upper before...