Simple question, that for the life of me I can't find the answer to. Does the extension tube type matter for a particular stock? Meaning, would a stock (VLTOR, Magpul etc.) work with either a 5 or 6 position buffer tube, or does the stock require a certain one? My first EBR has an A2 stock, so this is new territory. I'm glad I at least thought about it before clicking "purchase"