When I was assembling the buffer tube to the lower receiver, I ran in to ( what I think) is a problem. There is a notch in the buffer tube that the buffer tube pin fits into. However, when I turn it in enough for the pin to fit into that notch, there is about a 16th of an inch overhang, and I am unable to close the upper on to the lower. Suggestions on whether to leave it like that ( with it backed out enough to close, but not have the pin seated into the notch), or to file away a little bit of the tube so that the pin seats into that notch.

Thanks!

There shouldn't be any tube over lapping into the receiver. Screw the receive extension (buffer tube) in far enough to keep the buffer detent secured in place w/out over lapping from the tube. Your upper should be able to close w/out issue if this is done. If the tube's screwed too far inward the buffer detent prolly won't be able to move up & down. It doesn't take a lot of over lap to keep the detent securely in place. Pics of your situation would be nice if you can post them.

I will get some pics up in an hour or so. Thanks!