Newbie question about M-16 uppers

[moleman]

I've been following this post and I looked through all 6 uppers I have, and my buddies rifles. We checked rifles made by: bushmaster; colt; Olympic arms; SGW; Palmetto arms; Armalite;and Eagle arms. I have yet to find an upper receiver without the auto sear cut out on the bottem of the upper receiver just forward of the rear hinge pin block. I think all the forged upper receivers are machined to M16 specs. You can see the cut out illustrated clearly in the P.O.F. add for their CROS fininish on the inside of their receivers (the back of the July 20 shotgun news has a full page color add). I understand the bolt carriers are different between an M15 and AR15, but aren't we talking about the actual aluminum upper receiver here? If someone has a picture of an AR15 without the auto sear cutout on the UPPER RECEIVER please post a picture of it.

[sniper69]

Not sure what you are trying to say? It would appear as if you just contradicted yourself though. The 1st line you are saying it can't be done??? The last line you mention enthusiasts who are doing it??


I never said "it is illiegal don't do it" I said it goes quite aways towards making a "readably convertable weapon". The link does not address modifications to the receiver... only that M16 parts in your AR15 is not legal.

The link states: An example of a firearm meeting this section of the definition is a semiautomatic AR15 rifle possessed with an M16 bolt carrier, hammer, trigger, disconnector and selector. If the semiautomatic AR15 is assembled with the described M16 parts and the rifle is capable of fully automatic fire, the weapon possessed in conjunction with the M16 parts, whether assembled or not, is a machinegun as defined.17

I'm not disputing this. I'm saying this is not fully cover the issue. It does not mention modifications to a receiver at all. So if the link was the only way to be in violation of the law then I can drill the hole for an auto sear but as long as I don't have an auto sear that is OK!! I don't know whether you can you use an M16 upper for an AR build but I do know that anything you do to an AR lower to make it accept an Auto Sear turns the receiver from an AR to an M16. Modifying it to fit an M16 upper would do this.

Well let's take this a step further.
If you use the M16 bolt carrier, hammer, trigger, disconnector and selector as outlined in the ATF link previously posted the gun will fire more than one shot with each pull of the trigger (although it probably wouldn't be safe). This is assuming that the selector isn't on safe or fire but is moved past the fire position (which an M16 selector allows). This is because with the trigger held back it wouldn't be able to catch (unlike when an AR FCG is used) and would cause the hammer to keep going forward until the trigger was released (at least the way I understand it). Using a R.D.I.A.S. (Registered Drop In Auto Sear) would make for the safe use of those parts in an AR for full-auto and is legal. Not using a D.I.A.S. that is registered is obviously illegal. A R.D.I.A.S. doesn't need a hole drilled in the receiver for it to work. Or one could just buy an M-16.
Just using an M16 upper wouldn't be a problem - the problem comes when the other M-16 parts are installed in the lower. If someone is feeling anal they could use an AR bolt carrier in the M-16 upper and along with the AR parts in the lower there would be none of the parts listed in the link - hence no full auto. Why make it complicated?????

[Coils]

Not sure what you are trying to say? It would appear as if you just contradicted yourself though. The 1st line you are saying it can't be done???

He's asking you "How would you modify an M16 upper to fit an AR lower???" because in your post (#27) you stated "If you modify an M16 upper to fit an AR15 lower". As far as I know the only difference between an M16 & AR15 upper is the early model M16 used a larger front pin, there might be more differences but this is the main one I know of that needs addressed to mount the two together, other then that that fit together.

I never said "it is illiegal don't do it" I said it goes quite aways towards making a "readably convertable weapon". The link does not address modifications to the receiver....

No you never said "don't do it".
Doing mods to the upper itself doesn't mean anything, you can mod it to take a completely different bolt if you want (let's say a square one). The lower is a different story, any mods to allow FA parts to function in an AR is illegal.

... only that M16 parts in your AR15 is not legal.

Exactly. The ATF has done a lot of testing and feel (and most likely proved) that simple installing FA fire control parts, even if there is no auto sear, you can make an AR fire multiple shoots with one pull of the trigger.

1) but I do know that anything you do to an AR lower to make it accept an Auto Sear turns the receiver from an AR to an M16. 2) Modifying it to fit an M16 upper would do this.

1) That is correct
2) Modifying what, and how are you modifying it?


Sorry if this reply sounds like an argument but it's not, I'm trying to see your point of view and what you mean.

[sniper69]

So if the link was the only way to be in violation of the law then I can drill the hole for an auto sear but as long as I don't have an auto sear that is OK!!

Common sense says not to drill any holes in a receiver that would allow it to be converted for full auto use. Drill the hole and see what happens. It won't magically make your gun full auto - but it will put you in violation of the law. No one said the link had all scenarios covered - just what M16 parts couldn't be used in an AR.

I don't know whether you can you use an M16 upper for an AR build but I do know that anything you do to an AR lower to make it accept an Auto Sear turns the receiver from an AR to an M16. Modifying it to fit an M16 upper would do this.

I'm assuming that you mean modifying an M16 upper to fit an AR lower will make it accept an auto sear. So all I will ask is HOW???? Usually the only mod to use an M16 upper with an AR lower is to possibly drill one of the takedown pin holes larger (for doing an early colt reproduction). Later M16 uppers have the same size holes so it should fit on an AR lower with no problems.



Also - it is noted that an M16 FCG can be modified to look like an AR FCG for legal use. This obviously involves some grinding or milling - but until the work is done could it be considered illegal?

[3/325]

Well let's take this a step further.
If you use the M16 bolt carrier, hammer, trigger, disconnector and selector as outlined in the ATF link previously posted the gun will fire more than one shot with each pull of the trigger (although it probably wouldn't be safe). This is assuming that the selector isn't on safe or fire but is moved past the fire position (which an M16 selector allows). This is because with the trigger held back it wouldn't be able to catch (unlike when an AR FCG is used) and would cause the hammer to keep going forward until the trigger was released (at least the way I understand it). Using a R.D.I.A.S. (Registered Drop In Auto Sear) would make for the safe use of those parts in an AR for full-auto and is legal. Not using a D.I.A.S. that is registered is obviously illegal. A R.D.I.A.S. doesn't need a hole drilled in the receiver for it to work. Or one could just buy an M-16.
Just using an M16 upper wouldn't be a problem - the problem comes when the other M-16 parts are installed in the lower. If someone is feeling anal they could use an AR bolt carrier in the M-16 upper and along with the AR parts in the lower there would be none of the parts listed in the link - hence no full auto. Why make it complicated?????

Good point! However, there are two flaws. 1, in order to function in the full auto mode you need an auto sear (either the M16 one or a drop in auto sear). Without the sear the hammer just follows the bolt forward and will not fire the 2nd round. It will "ding" the primer but not enough to fire it (most times). 2, a RDIAS is meant to convert an AR without drilling the hole for an auto sear and without making in modifications to the upper either. A DIAS is in the center of the bolt channel not off to the side like on an M16. An M16 upper has a slot cut on the side about an inch forward of the lug for the take down pin. It is about 1/4 long and about 1/8 in. deep. I have never seen it on an AR upper.

[3/325]

1) That is correct
2) Modifying what, and how are you modifying it?


Sorry if this reply sounds like an argument but it's not, I'm trying to see your point of view and what you mean.

I meant if you change the take down pins to accept an M16 upper because the would be a change to the lower. If you place shims in the M16 upper than that would just be a modification to the upper and not the lower.

I'm not trying to argue either. It's just that I've seen alot of people ask "is this legal??" type questions online. Most of the time if it is "how many parts do I need to make my AK US made" that is all good. But when people start asking questions about NFA weapons or what modifications can be made to their weapons.... they should be asking the ATF or some other source. Because when it comes to laws & regs internet forums are not the greatest source of info. If you wound up in court; citing a posting on a forum won't do you much good. I'm sure alot of poeple probably really do know what is legal in their area but the person asking the question may be in a totally different state or county or city where it would be illegal.

[sniper69]

Good point! However, there are two flaws. 1, in order to function in the full auto mode you need an auto sear (either the M16 one or a drop in auto sear). Without the sear the hammer just follows the bolt forward and will not fire the 2nd round. It will "ding" the primer but not enough to fire it (most times). 2, a RDIAS is meant to convert an AR without drilling the hole for an auto sear and without making in modifications to the upper either. A DIAS is in the center of the bolt channel not off to the side like on an M16. An M16 upper has a slot cut on the side about an inch forward of the lug for the take down pin. It is about 1/4 long and about 1/8 in. deep. I have never seen it on an AR upper.

3/325 I can see your point but stranger things can happen - I'm sure the ATF has a reason as to why they don't want those specific M16 parts in an AR. Also with point number 2 - please reread my post where I wrote " A R.D.I.A.S. doesn't need a hole drilled in the receiver for it to work".

As for differences between AR's and M16's quarterbore has a nice site with pictures and explanations. http://www.quarterbore.com/nfa/dias.html and http://www.quarterbore.com/nfa/registeredreceiver.htm

[sniper69]

I'm sure alot of poeple probably really do know what is legal in their area but the person asking the question may be in a totally different state or county or city where it would be illegal.

It is best to be safe and not sorry.