I remember reading someplace the the bolt & bolt carriers in USGI M16's are stronger then the ones that are available for the commercial AR's. Personally I can't see why that would be the case. Is this a myth or is it true?

My next question is is it LEGAL to JUST have a M16 bolt and bolt carrier installed and NO OTHER M16 parts on the rifle or owned?

Thanks
Wolfie

Well, I've heard that the USGI Bolt/Carrier assembly was heavier, thus giving more reliable operation.

But I've also read the disclaimers from the vendors stating that just ONE USGI part in an AR15 is illegal - so I'm not going to try it!

It might be a solution in search of a problem though, because my BUSHMASTER never hiccups anyway.

That's interesting... one USGI part in an AR15 is illegal?  But an M14 bolt, op rod, trigger group, barrel, flash supressor, etc. is perfectly legal for an civilian clone like the Springfield M1A.  And the M14 is considered a machine gun, too.  

I believe ATF has ruled that anyone possessing both a semi-auto AR-15 (or clone) and any full auto parts has, in their view, a machine gun.  I’m not sure they could ultimately enforce this, but I have no interest in full auto parts anyway.

By the above, having an unmodified M16 bolt carrier in an AR could cause you a problem.

I don’t think the bolt would since it has nothing to do with the full auto capability.  I believe USGI parts other than those associated with the full auto capability are not a problem in an AR (excepting putting pre-ban parts on a post ban AR).

Bushmaster covers the differences between full auto and semi-auto only parts in some detail in its catalog.  This is probably also covered in their website.

To the ATF, a machinegun is a machinegun AND/OR a combination of parts that will allow more than one shot to fire with one pull of the trigger, even if not reliably.  So, a worn, malfunctioning semi can also be considered a machinegun.

So, let's go over this part by part.

There is no differnce in the M16 and AR15 bolts.  The bolt carriers are different.

The bolt carrier:  The M16 bolt carrier has a surface on the bottom rear which is meant to trip the autosear of a full auto version.  This is ground away on the AR15 carrier so that even if a GI autosear, or a drop in autosear were added, there would be nothing to trip it.  In addition, just in case someone tried to remove the disconnector and get the AR15 to fire full auto (which is barely possible with very soft primers), there is a ramp machined up toward the  head of the firing pin.  The idea is that the notch on the hammer will catch on the head of the firing pin and prevent the bolt from moving forward if the disconnector does not catch the hammer.  Thus, an M16 bolt carrier alone, with the removal of the disconnector, and soft primered ammo, MAY allow a double.

Hammer:  A notch is machined in the top front of the hammer (see above).  The autosear spur is machined off.  If an autosear were present, and a drop in autosear used, and a bolt carrier conversion used (that is a screw on autosear surface-see Bushmaster catalog, replaces part machined off AR15 bolt carrier) could make a full auto weapon.  (Grinding the autosear spur off the rear of the hammer alone is enough to be a legal AR15 hammer)

Trigger:  Slot in rear of M16 trigger could allow installation of full auto disconnector.  This one part alone is iffy.

Disconnector:  Can only be installed if there is a M16 trigger with slot in back.  These two are also iffy, by themselves.

(Commercial AR15 triggers and disconnectors are made by shearing or grinding the tail off the disconnector, and welding up the slot at the rear of the trigger.)

Well, they have all sorts of theories for all of the parts.  Yes, it stretches the imagination.

Its probably not a good idea. I think the bolt is legal (the carrier is iffy though). To put it short I wouldnt tempt fate.

Any part of the trigger group is iffy like 199 said.

IMHO the barrel is gonna wear out before the bolt. Even if it does corrode to the point of not being able to function they arent that expensive to replace.

I dont think they will arrest you for using M16 furniture tough.

You guys are wrong about M16 parts in an AR15 being illegal.  They are illegal only IF they allow full auto fire.

Go to the Legal Section of the General Discussion Forum for an in depth discussion of this issue moderated by Steve in VA, a practicing lawyer familiar with this issue.

The M16 carrier is NOT ILLEGAL in an AR-15.

There is a good post about this which is tacked in the Legal forum.

Moreover, I know that many highpower competitors will use an M16 carrier in their rifle. They like them for the added mass.

IMO, I think that the added material of the M16 carrier would theoretically make it slightly more rigid, and durable. However I think this would have a neglible effect on the rifles functioning.

You can't have any M16 parts in an AR, period.  It is considered a machine gun then, and would be unregistered. (ie, bad.)  There are some states, such as good ole CT, where you are not supposed to even possess any M16 parts when you own an AR, just like the DIAS laws.

Please state the law, regulation, or opinion letter that states that.

Because the opinion letter from the Tech Branch posted here:
[url]http://www-2.cs.cmu.edu/afs/cs/user/wbardwel/public/nfalist/atf_letter52.txt[/url]

This is their definition:

Pay carful attenion to that last clause [b]if the rifle shoots automatically when the components are installed.[/b]  Installtion of an M16 carrier does not allow the rifle to shoot full-auto.

They do recommend you don't have any [b]fire control components[/b] (further down in the letter).  Its a CYA move and most people abide by it.  The bolt carrier is not a fire control component.

This have been covered extensively by Steve (moderator of the Legal formum and a Laywer versed in this kind of law).  He'll sate the same - its OK to put the bolt carrier in your rifle, but as a CYA you shouldn't have any unneutered M16 parts.  

Everyone who is interested in this should read the thread in the Legal Forum:
[url]http://www.ar15.com/forums/topic.html?b=1&f=6&t=147440[/url]

Wow I love that thread. Much more interesting than any Rguns thread ive ever seen. lol.

It is perfectly legal to put an M16 carrier in an AR, and every AR I've ever had had an M16 carrier installed. Why?  Because the heavier wieght of the M16 unit means the rifle operates at the speed it was designed to operate at.  The typical AR15 bolt/carrier assembly is enough lighter to cause more wear on the rifle, from its' slamming back and forth faster during operation.

That being said, I've always covered my butt by grinding back that shoulder on the underside, just enough so it won't trip an auto sear any more.[:D]

By the way, that cutaway under the firing pin, which was never mandated by the feds (purely Colt's idea), is apparently being quietly dropped by Colt and at least some of the aftermarket people.  We've had recent postings that late model Colts don't have it, and I just bought a DPMS lower that came with an un notched hammer, indicating that they aren't using that cutaway carrier either.