I'm trying to remove my old A2 buffer tube from the reciever to install a new collapsable stock, and for the life of me, i cannot get the tube to unscrew. These aren't reverse threads are they? I could use some suggestions as i have to be so very careful not to damage the lower, its a registered preban in calif. If i mess this lower up, i'm done here.

They are installed using a right handed thread.  I have heard of people putting uppers in the freezer overnight to loosen stuck barrel nuts (never tried it myself, but I heard that it works).  I don't know if that would work on the receiver extension or not.

Might try a good quality penetrating oil, and maybe just a SLIGHT amount of heat from a torch...not too much to weaken the material, just warm it up in hopes it comes loose.

Good luck.  

Thanks, i did put some clp on it, and is letting it set, we have some spray at work that the mechanics use to free up nuts and bolts on diesel engines, i might try some of that. It has never been removed, so i imagine that all the heat and carbon build up probably has it locked down pretty tight.

I encountered the same problem last week with a bushmaster. Started out with a small screwdriver and only managed to partially strip the scew and both bend and break the screwdriver! I ended up going to sears and getting the biggest QUALITY screw driver I could find [Craftsman 3/8" 10" for $9]. The blade fit perfectly in the screw slot and after l put the gun upside down with the muzzle (brake) on the ground I leaned on the screw driver and clenched down and managed to loosen it. Wasn't easy but it just took a little convincing. Bracing your knees against the magwell or pistol grip helps prevent the whole gun from turning under torque.
Good luck
Ryan

it was probably loctited at the factory. use some heat and it will then come right off

I got it off guys,thanks for the help. I just tapped on the spanner wrench while putting a little pressure on it. It took a little while, but it finely loosened up.