Armalite makes good products but be advised their uppers will likely not fit any other lower. I have a friend that machines uppers and lowers and his lower will take the Armalite upper but it will have a gap at the bottom where Armalite machines their diagonal at the rear end. It does not affect the operation but you can see daylight under that diagonal. Armalite stuff is proprietary and patented.
There are so many companies making AR stuff it would be advisable to check what you are ordering to make sure it will fit.
