I'm trying to remove a RRA arms "Entry Stock" and replace it with a fixed telestock.  I cannot determine how to remove the old tube from the lower receiver.  It seems like it's glued on or something is holding it besides the threads.  I removed the Entry Stock with ease, but that's where I got stuck.  The black tube which houses the buffer spring that the old stock attaches to will not budge.  I've even tried channel locks, but stopped because I was putting teeth marks into the aluminum.  Anyone else run into this problem?  Thanks.

BD

I assume you are referring to the receiver extension tube, aka buffer tube.

There should be a squared-off nub at the rear end.  Use correct-sized wrench and unscrew.

-z