Black Rifles 2nd Ar build


Started my second ar build. So far I have a spikes tactical lower, dpms lower parts kit and a a2 stock. The upper is a stripped bushmaster and the barrel is a 20" heavy barrel. So far thats it still have to get the charging handle, free float tube, and some small pieces for the upper. I am looking for a round free float tube. Can anyone tell me where I can find a simple round free float tube with a swivel stud on the end? I am going to put a bipod on it.I am just looking for a basic one.