Building AR15 pistols with carbine reciever extensions

[E-man930]

As far as I'm concerned, this is a no no... am I thinking clearly?

See this excerpt from a fudd forum:

"I'll repeat that it is not a crime to possess a pistol with a carbine buffer tube and a stock which may readily slide on said buffer tube. In fact, since reg 2011-4 it makes sense to build a pistol with a carbine buffer tube. That way it would readily accept a stock once a 16 inch barrel is installed on the receiver."

Thanks for your time.

E-man