Excuse me if this has been answered before but I have been unable to find a definite answer with legit documentation.

I would like to build a 300 Blackout Pistol. I have seen many built lowers online for very good prices. I am aware I could get the stripped lower and build it but some of these prices are great.  My main concern is the fact that they are built with the stock already attached.

What makes the AR lower a rifle? Attaching the stock, adding an upper and shooting it in that platform? Does the lower with a stock mean its a rifle forever even though it hasn't touched an upper?

The FFL will transfer it as "other" on the 4473 for me but I'm worried because they come with the stock added.

Thanks in advance for any assistance. If it doesn't work then I will get a stripped lower.

So you buy a "virgin" lower from a FFL w/ the stock attached.  It's marked "other" on the 4473.

It's never been assembled as a rifle.

Remove the stock.  IF you have other long arms in your possession that will accept an AR stock, set it aside.  IF you have no other long arms that will accept that stock, sell it or give it to a friend.

Install your sub 16" upper.  You're good.  You have a legal AR pistol.

Buy a 16"+ upper, or 14.5" pinned & welded, etc.  Pick up your former stock from your friend, install the 16" upper first, then install the stock.  You're good.  You have a legal AR rifle.

Remove the stock, then remove the 16" upper.  Install the sub 16" upper.  You're good.  You have a legal AR pistol again.  You also have a spare stock, which clearly is intended to only be installed when you have your 16" upper installed.

Swap back and forth as you like, just remembering to remove the stock before installing the sub 16" bbl.

Thank you Backbencher. There is so much conflicting information out there. Many forum posts state that the stock alone messes everything up and it becomes a rifle when a stock is added. I found a letter from the ATF that basically stated that if no upper had been attached then it is NOT a rifle. However, the date was from 2004 and it seemed as if some other documents from the ATF were conflicting with that information. The ATF uses very confusing wording.

They have a very confusing law they have to interpret and enforce.  Fuck FDR.

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