Buffer tube - full length - ? thread size ?
I'm trying to put together and buy parts for an AR 15. I'm having a hard time comprehending this buffer tube situation. I have a MP 15 lower receiver. I'm looking to buy a full length buffer tube, and put an A2 stock on. Now, so I believe, the major diameter of the male threads on milspec tube is 1.185, and commercial tubes threads are 1.170, difference of .015
This seems like alot. I want a good fit where it threads together. Now, someone just broke news to me full length buffer tubes arent milspec or commercial. If this is true, what thread size is it? What do i need to thread into my S&W mp 15 please??