At least for wearing a t-shirt and shooting at the range. I would like a stock that allows a longer length of pull. Here's a picture of the stock that is currently on the rifle: [img]http://www.adcofirearms.com/rra/Tactical%20buttstock.jpg[/img]

Now, this being my first AR, I'm not sure how all of this works. I screwed a big metal tube into the back of my lower receiver. Then, the stock fits over the tube and a screw goes in through the butt-pad and into the end of the big tube. I keep hearing people talk about a buffer extension. I don't know what that is. My question: what all needs to be replaced if I go with a longer stock? Will I need a new buffer tube/buffer/spring etc? And where does the buffer extension come in to all of this? Thanks!

You will likely have to replace the buffer tube (the big tube thing you screwed into the receiver) when you put a longer stock on.  Since the stock usually screws to the back of the buffer tube, it has to be longer.

So if you look at say, an A2 stock, make sure you get the buffer tube with it.  (and probably the buffer and spring)

If you get a collapsible or fake collapsible stock, then the tube is PART of the stock, so you just need the buffer and spring.  

Hope that helps!

The tube that comes off the back of the receiver is the "receiver extension," AKA "buffer tube." If you have the short one you were using with short entry stock, and you want to put a normal-length stock on, you need a full size receiver extension, and a new recoil spring and buffer.

If you are putting an A1 length stock on, that is it.

If you are putting an A2 length stock on, you need to also add a spacer, which is a little piece of metal that sits on the back of the receiver extension, to account for the slightly longer length of the A2 butt stock.

Whichever one you use, make sure that the screw has a hole in the middle. This is to relieve pressure in case water ever gets into the receiver extension (which should not usually come up). While NOT having the hole probably would not cause trouble most of the time, it COULD cause a catastrophic malfunction, or at least that is what they told me at Armorer's school.

Take care when you remove the butt stock. The stock also holds a small detent and spring in place that keep your rear takedown pin from falling out. If you aren't careful, you will lose the pin and maybe the spring (even if you are careful, you WILL lose one eventually). When putting the buttstock back on, it is also possible to kink the spring, so be careful and push the stock on straight.

There are also fake telestocks for your weapon (I am assuming it is a postban), that you can add, but that is a tad more complicated.