Ok I just got done putting my lower together. I put my buffer tube on and noticed that it has a little exstition on it that when screwed in to where it it set straight the lip will sit on the edge of the buffer retainer. If I screwed it in a little more then it would rest right up against the little tip and I could not get it to turn all the way doen to put the position holes on the bottom. I unscrewed it until the holes are on the bottom but it looks like the tube is just on the edge of the retainer and I am a little confussed. I have seen the LMT tubes and some others like that and they do this and I am just wondering if the tube is not to spec and will cause problems later or if it is good to go. I have also seen some tubes that do not have that little extra lip on them and they seem to go over the retainer just a little bit more.

If you have the buffer tube receiver extension unscrewed to where the latch holes point straight down and it is still capturing the buffer retainer you are fine.  Tighten the plate and castle nut down and try to wiggle the buffer retainer with the tip of you finger.  If it doesn't pop out, you're okay.  The tolerances of the lower receiver, receiver extension and the buffer retainer all come into play here so it's not unheard of to have the tolerances stack into an unacceptable/failure condition.

I have an LMT that goes right up against the tip of the buffer retainer and a Kaiser Defense that sits just on the edge.  Both work fine.

Ok thanks I guess I am just so used to the tubes that don't have the little lip thing on them. I have played witht he retainer with my finger and it stays where is it supposed to and does not try to come out so I guess I am G2G then.

Having the same problem with an Armalite tube. just barely covers the edge of the detent.