What makes an AR-15 an M-16?

[Sgt.K]

I saw a guy selling M-16 lower parts at Oaks and found myself curious, then I got an email today about a retailer selling M-16 LPKs.

I know the third hole will get a lower pegged as full-auto, but how many FA parts can I cram into my new lower before I have to notify ATF?

Supporting citations welcome...

[SgtRecon]

basically, the third hole as you mentioned, and the auto sear that goes there. plus the fire control group. the disconnector, safety and hammer are different than the semi's plus many of the lowers are milled to prohibit the "drop in" of an auto sear. Some very early Colt SP1's have all the auto goodies installed without the pocket milled in the lower for the auto sear. Also the bolt carrier under belly is shortened so as not to engage any sort of OEM sear or home made DIAS (drop in auto sear)

Here is a great animation video of how an M-16 works and explains the differences:

https://www.youtube.com/watch?time_c...&v=wMIBUIN30yU

[Sgt.K]

basically, the third hole as you mentioned, and the auto sear that goes there. plus the fire control group. the disconnector, safety and hammer are different than the semi's plus many of the lowers are milled to prohibit the "drop in" of an auto sear. Some very early Colt SP1's have all the auto goodies installed without the pocket milled in the lower for the auto sear. Also the bolt carrier under belly is shortened so as not to engage any sort of OEM sear or home made DIAS (drop in auto sear)

Here is a great animation video of how an M-16 works and explains the differences:

https://www.youtube.com/watch?time_c...&v=wMIBUIN30yU

Good answer, thanks for taking the time.

I understand the mechanics. I'm more asking about the legalities. Specifically, as long as I avoid the auto sear and its spring, what other parts can I have before I'm running afoul of the NFA?

I've seen video of a registered DIAS. It won't function unless the lower has the auto hammer, and (probably) the disconnect and the auto safety.

[Gunsnwater]

Limbo limbo how far can you go? A hole and an auto sear are no no(s). Why do you ask?

Don’t buy fa sears. Just my opinion. I like to give the edge plenty of room.

[GOYABEAN]

can't have nothing

[Gunsnwater]

Nice

[DucatiRon]

can't have nothing

I hope your joking. 98% of AR's out there are probly running FA BCG's. Or at better semantics " Bolt Carrier".

[GOYABEAN]

I hope your joking. 98% of AR's out there are probly running FA BCG's. Or at better semantics " Bolt Carrier".

Yes

[USMC3531]

Myself I wouldn't put the safety or disconector in, because if you put it in the 3rd position it could fire more than 1 shot per trigger pull. Most likely you will get q jam and light strikes but..... so imho you could use the hammer and trigger but that's it.

[Justin///M]

Myself I wouldn't put the safety or disconector in, because if you put it in the 3rd position it could fire more than 1 shot per trigger pull. Most likely you will get q jam and light strikes but..... so imho you could use the hammer and trigger but that's it.

This is it, really. Besides a 3rd hole receiver being considered a machine gun, the rest goes back this definition. There's lots of information on this out there. Some people say don't bother having anything, others say simply don't put enough together to cause more than one shot per trigger pull.


Here's a 1999 letter in which they say,

"The definition of machinegun in section 5845(b) also includes any
combination of parts from which a machinegun can be assembled if
such parts are in the possession or under the control of a person.
Thus, an AR-15 rifle possessed with separate M-16 machinegun
components can meet the definition of a machinegun, if the rifle
shoots automatically when the components are installed."


And,

"We would advise any person who possesses an AR-15 rifle not to
possess M-16 fire control component."


http://www.titleii.com/bardwell/atf_letter52.txt




They've spoken like the 2nd quote many many times, but not because they're saying that possession of those items in and of themselves is illegal, but the accumulation of enough parts in an AR15 can cause was USMC3531 said. They're advising that people don't unwittingly manufacture an unregistered machine gun.

Here's another such letter,


"We therefore strongly advise against the stockpiling of additional M-16 fire control components."

http://www.titleii.com/bardwell/atf_letter55.txt

And when you read it in its entirety, the context is in the realm of not unwittingly making an illegal machine gun.



This letter seems to drive it home, that you can own all the fire control parts of an M16, so long as you don't ever cause your AR to fire more than one shot per trigger pull..., again, simply going back to what USMC3531 said. See question 3-8, the ATF continues to warn AR owners to not accidentally run afoul by putting M16 parts in their rifles. The last paragraph of the answers to 3-8 sums it up.