I ordered an A1 stock from Northridge for my build, and had one question:  I take it the top screw on the trapdoor is what retains the stock on the weapon (i.e. it threads through the buffer tube?)

Another question out of curiousity: my understanding is that CAR buffer tubes have holes drilled in them to determine the stock locking positions?  Is this small pin/hole the only bearing point of the whole collapsible stock?  

Thanks Troy.  As usual, you know the answer to any question I can come up with!

Dawg