I'm planning to remove and replace an A2 buttstock with a post-ban non-collapsable carbine buttstock.
I don't yet have a multi-tool, but have one on order and should arrive in a couple of days.
In the mean time I have already removed the buttpad from the A2 and removed the outer shell of the buttstock leaving only the receiver extension. I was careful to save the takedown pin spring that was hanging loose.

What is the proper way of removing the receiver extension? What part of the multi-tool do I use if I even need it at all and what part of the extension do I use the tool and what way do I turn(clockwise, counterclockwise?) or press to remove the extension. The extension is round all the way to the receiver and can't figure out where I would grab it to turn it.

The non collapsible butt stocks use the same buffer tube as the A2 stock.

Multi-tool has a slot that'll fit the "end" of buffer tube flats. Righty-tightey, lefty-loosey.

Mike

This should help, very easy to follow. http://www.ar15.com/content/docs/assembly/lower/