Since the lower is the machine gun can I put a modern upper on a class III M16?

[specizripn]

I am looking into purchasing a transferable M4 or M16 and I understand the purchasing process and cost already, but I was wandering about making a few changes. Isn't the lower receiver technically the machine gun, so couldn't I put a modern upper receiver on the gun legally? I like the modern ar style uppers with rail mounts better than the carrying handle sights on most of the pre86 guns. If so wouldn't I need the bolt carrier modified to an open bolt-carrier?
Thanks

 

[shotgunjoel]

You are correct that the lower is the machine gun and that you can put on any upper that you please. The M16 doesn't use an open bolt design, but you would need an M16 bolt carrier in any new upper. I suppose that you could use the carrier from the current upper on the M16 and put it into any modern uppers that you buy.

 

[specizripn]

Thanks so much, thats exactly what I was looking for!

 

[jmorris]

Will add even otherwise SBR uppers are OK without another stamp.

 

[AlexanderA]

Regarding the bolt carriers, I would add that FA bolt carriers are legal even in semiautomatic guns (per a letter ruling from the ATF to Colt), and that in fact many new semi guns are sold with FA bolt carriers.

The beauty of the AR-15/M16 design is that it's completely modular. If you have a registered FA lower (including a registered DIAS or LL), you can use any style, length, or caliber upper.

 

[specizripn]

Cool, thanks guys! You're all very helpful!

 

[Prince Yamato]

Actually there are open-bolt ARs. I forget which models. They exist though.

 

[Quiet]

Actually there are open-bolt ARs. I forget which models. They exist though.

Colt/Diemaco M-16A2 LMG

Made during the 1980s for the Canadian Army Squad Automatic Weapon trials. It lost out to the FN Minimi.

 

[CmdrSlander]

Land Warfare Resource Co. makes the M6A4 SAW which is a gas piston AR which fire from an open bolt. http://www.lwrci.com/p-130-m6a4.aspx