Ar15 pistol upper to rifle lower

**mickey01023** · November 3rd, 2012, 05:06 PM

How easy is it to transfer a pistol upper to an ar15 lower? Just pop the pins or is it more involved than that?

I know the laws when it comes to sbrs

**bigredxlt** · November 3rd, 2012, 05:16 PM

Originally Posted by mickey01023

How easy is it to transfer a pistol upper to an ar15 lower? Just pop the pins or is it more involved than that?

I know the laws when it comes to sbrs

A pistol upper is just a regular ar-15 upper usually with a short barrel and shortened gas system.

**wellcraft** · November 3rd, 2012, 06:12 PM

the upper receiver on a pistol is the same as the upper receiver on a rifle so a pistol upper should fit any lower unless one of the two has none standard push pins.

**LightningMcQueen784** · November 4th, 2012, 11:14 AM

However, you must be careful to not put your pistol upper to a rifle lower without proper SBR paperwork and tax stamp.

At least to my understanding.

The second you put your pistol upper (I assume it's got a short barrel, <16"), you've built an SBR.

I know you said you know the SBR laws.... just wanted to reiterate and make sure

**tonyfac** · November 4th, 2012, 12:54 PM

your pistol upper must be put on a virgin lower. as mentioned, you will create an sbr with a previous lower. according to the law, if have a virgin lower, and in your basement you attach a rifle upper to see what it looks like, and then take it off, that lower can no longer be used for a pistol now because it was a rifle.

insane rules, atf at it's best.

**RXM** · November 4th, 2012, 02:17 PM

Originally Posted by tonyfac

...if have a virgin lower, and in your basement you attach a rifle upper to see what it looks like, and then take it off, that lower can no longer be used for a pistol now because it was a rifle.

From my discussions with the ATF Firearms Technology Branch earlier this year, to be a considered a rifle, the virgin lower must have both a barreled upper receiver (>= 16") AND a stock attached. Just having a barreled upper attached to a virgin lower receiver (without an attached stock) does not make it a rifle. A rifle is designed to be fired from the shoulder. Without a stock attached, the firearm is not designed to fire from the shoulder.

I have zero documentation on this as it was a phone discussion. I'm sure there is information floating around the web that clarifies this.

**cellboothmgr** · November 4th, 2012, 02:48 PM

there was also a discussion on here about this topic. if i recall, you can build an ar pistol, then convert it to a rifle, and back to a pistol without issue. however, if it starts as a rifle it cannot go to a pistol without sbr paperwork. im sure someone with better google skills would be able to find the link...