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Posted: 1/30/2006 12:17:13 PM EDT
I've seen M16 bolt carriers advertised. What advantage does it give over an AR-15 carrier? Is it just the cool factor or is there are real technical advantage to the M16 carrier?

This NOT a thread about legal issues! If you have a question or comment about the law, do a search.
Link Posted: 1/30/2006 12:18:16 PM EDT
slightly heavier
shrouded firing pin



Link Posted: 1/30/2006 12:19:50 PM EDT

Originally Posted By eklikwhoa:
shrouded firing pin

???
Link Posted: 1/30/2006 12:30:33 PM EDT
the firing pin area is not exposed to keep the firing pin from hanging up on the hammer.
Link Posted: 1/30/2006 12:39:13 PM EDT
[Last Edit: 1/30/2006 12:40:17 PM EDT by eodinert]
Extra weight helps delay unlocking of the bolt when a cartridge is fired. This allows time for the pressure to drop before extraction begins. Normally, this is not needed, but in short barreled guns it can help a bunch.

On many AR15s, the bolt carrier is cut away under the area where the hammer hits the firing pin, exposing the head of the firing pin to the hammer on the return stroke of the bolt carrier. The hammer, on said guns, has a 'hook' of sorts cut into the top of the hammer that catches the head of the firing pin, usually wonking your firing pin retaining pin. The purpose of this mod was to prevent slam fires caused by people modifying their guns to fire full auto. Since an AR won't fire if the hammer rides the bolt home anyway, it was pretty stupid. Only certain manufacturers insulted us with this modification.
Link Posted: 1/30/2006 12:47:43 PM EDT
The weight issue is often sighted, although I'm half tempted to believe that it's internut myth.

I like the shrouded firing pin collar, although it is a little more difficult to clean. I run 16 carriers in most of my guns.
Link Posted: 1/30/2006 1:01:05 PM EDT

Originally Posted By eodinert:
The hammer, on said guns, has a 'hook' of sorts cut into the top of the hammer that catches the head of the firing pin, usually wonking your firing pin retaining pin. Only certain manufacturers insulted us with this modification.



Yep, my Colt LE6920 came like this......
Fuctions perfectly but the retaining cotter pin gets bent and is harder to reinstall. Bought a couple extra cotter pins incase I can't get bent ones back in.
Link Posted: 1/30/2006 1:04:33 PM EDT
Link Posted: 1/30/2006 2:15:04 PM EDT
shrouded firing pin.

less reciprocating mass will make for a faster second shot. not more.
Link Posted: 1/30/2006 2:30:04 PM EDT
None that can be empirically documented.
Link Posted: 1/30/2006 2:30:36 PM EDT
[Last Edit: 1/31/2006 4:32:32 PM EDT by Rimfireguru]
Stupid comment
Link Posted: 1/30/2006 2:33:11 PM EDT
The shrouded firing pin advantage is no longer true since most current AR bolt carriers have the shrouded firing pin. As for the extra mass, the only difference you may notice is your rifle short cycling with low power (WOLF) ammo.
Link Posted: 1/30/2006 2:38:51 PM EDT
[Last Edit: 1/30/2006 2:39:58 PM EDT by SWO_daddy]
.
Link Posted: 1/30/2006 2:42:10 PM EDT
I think it's more a case of "why not". The carrier was designed a certain way for a reason, and cutting part of it off for no good reason just doesn't seem right.
Link Posted: 1/30/2006 3:18:53 PM EDT
I think the big deal with the larger mass of an M16-type carrier has at least as much to do with its speed AFTER the bolt unlocks as it does with slowing the unlocking process. It takes more energy (gas pressure over time) to move a larger mass, so it does make sense that unlocking time should be slowed down. But once that mass gets moving, it will move until something-the recoil spring-stops it. It will take longer for the recoil spring to absorb the kinetic energy of a heavier carrier, and longer for the spring to accelerate the carrier forward from a stop. This all adds up to materially slowing the cyclic rate-whether in auto or semiauto mode. A slower rate of fire equates to a less jarring, smoother operation.

With short gas system rifles (carbine length gas systems in particular) the gas from the gas port flows not only earlier in the cycle, but more forcefully, as it's tapped from closer to the chamber. Using a heavier carrier can help moderate the violence of such a rifle's functioning, and not only improve follow up sight picture acquisition, but really lessen wear and tear on the moving parts as well.

Just my 2¢ worth...
Link Posted: 1/30/2006 3:20:21 PM EDT
If you want a heavier carrier, David Tubb sells a weight system that fits in the back part of the carrier.
Link Posted: 1/30/2006 4:33:57 PM EDT

Originally Posted By edwin247:

Originally Posted By eodinert:
The hammer, on said guns, has a 'hook' of sorts cut into the top of the hammer that catches the head of the firing pin, usually wonking your firing pin retaining pin. Only certain manufacturers insulted us with this modification.



Yep, my Colt LE6920 came like this......
Fuctions perfectly but the retaining cotter pin gets bent and is harder to reinstall. Bought a couple extra cotter pins incase I can't get bent ones back in.




Mine too. Never had to keep spares on hand before, but I'm on my second one. I think I'll try the fully shrouded one in my next AR.
Link Posted: 1/30/2006 6:34:22 PM EDT

Originally Posted By Rimfireguru:
All of the above mentioned. No real price difference either. Why not?


Install all m16 parts in your ar (minus the autosear of course) and stick your tongue out at the gubbermint because it's legal




That isnt a very smart bit of advice. Hammer, disconnector, and selector will get you in BIG trouble, and are not necesary in a semi auto gun.
Link Posted: 1/30/2006 6:55:36 PM EDT
[Last Edit: 1/30/2006 6:57:12 PM EDT by Another-Bill]
I woud think the heaver carrier was designed to be heavy, to SLOW DOWN the cycle rate of the M16 as to not waste ammo and to produce better hits in FA. In a semi-auto I think the lighter bolt carrier is better to allow quicker follow up shots as the cycle rate is determined by the trigger puller. In IPSC I would NOT want a heavy bolt because I want to accuratly elimate all bad paper targets as fast as I can and never fail. Kinda like REAL LIFE except subsitute person for paper.

Bill
Link Posted: 1/30/2006 7:06:13 PM EDT
[Last Edit: 1/30/2006 7:06:30 PM EDT by SinistralRifleman]
Link Posted: 1/30/2006 10:51:51 PM EDT
I like using an M16 carrier so I can throw my upper on my friends M16 lower and hose some clay birds at 25 yards.
Link Posted: 1/31/2006 12:47:50 AM EDT

Originally Posted By SinistralRifleman:
I use full auto carriers with heavy buffers to make the action more smooth in all my rifles. Unless you shoot a lot you really won't be able to tell the difference with either part installed.



+1
Link Posted: 1/31/2006 4:31:17 PM EDT
[Last Edit: 1/31/2006 4:33:22 PM EDT by Rimfireguru]

Originally Posted By gmtmaster:

Originally Posted By Rimfireguru:
All of the above mentioned. No real price difference either. Why not?


Install all m16 parts in your ar (minus the autosear of course) and stick your tongue out at the gubbermint because it's legal




That isnt a very smart bit of advice. Hammer, disconnector, and selector will get you in BIG trouble, and are not necesary in a semi auto gun.



I do appologize.

I live in Canada where it's strictly the DIAS or other device that will get you in trouble.



Hammer, disconnector, and selector will get you in BIG trouble, and are not necesary in a semi auto gun


Neither is the m16 carrier but even less so I do understand.

I'm hearing conflicting statements and am just for my own account trying to find out what's legal and what's not for you southerners.

The law is pretty clear up here.

Link Posted: 1/31/2006 4:47:00 PM EDT

Originally Posted By STG77:
I think it's more a case of "why not". The carrier was designed a certain way for a reason, and cutting part of it off for no good reason just doesn't seem right.



+1
I like to use the proper parts in my weapon.
Link Posted: 1/31/2006 5:00:27 PM EDT
Anybody know the differance in weight between the M16 bolt carrier and the newer shrouded bolt carriers?
Link Posted: 1/31/2006 5:36:57 PM EDT
Link Posted: 1/31/2006 5:42:18 PM EDT

Originally Posted By David_Hineline:
The most important thing is it makes the conversion to fully automatic fire much easier.



Right after you file the firing pin down.



WIZZO
Link Posted: 1/31/2006 6:45:56 PM EDT

Originally Posted By Rimfireguru:

I'm hearing conflicting statements and am just for my own account trying to find out what's legal and what's not for you southerners.

The law is pretty clear up here.




In the US, we have law, case law, and BATF interpretation of the law.

The BATF considers possession of a semi-auto AR-15 rifle and M-16 trigger group components (hammer, disconnector, selector, and trigger) to be possession of an unregistered Class 3 weapon. The M-16 parts do not have to be installed in the AR-15, just in the possession of an individual who also possesses an otherwise legal AR-15. If you do not have an AR-15, possession of the M-16 parts is legal, since they are not legally a firearm (no receiver). Kinda stupid, but it's the BATF's position that possession of both means the individual has a criminal intent to construct a Class 3 weapon. That's the BATF's interpretation of the law.

If I'm not mistaken, the BATF has managed to get at least one federal judge to agree with them. That's case law.

So we have BATF interpretation of the law, and case law, so the actual laws don't mean much of anything concerning this issue. The BATF has all they need (their interpretation, and case law to back it up) to get a conviction (jail time, loss of certain rights, ruin your life, etc).

Make sense now?

Link Posted: 2/1/2006 1:30:51 PM EDT
The 'lighter' semi auto bolt carrier is the result of modifications to the regular, (i.e. class 3), bolt carrier. The FCG for an M-16 uses the front lip of the rear section of the bolt carrier to trip the hammer during full auto fire. With this part of the carrier removed, as well as the ramping of the underside of the carrier, it is more difficult to convert the rifle to full auto without additional modification. The use of a class 3 carrier is not in and of itself illegal, and is used by HP shooters to increase the mass of the rifle.


Originally Posted By STG77:
I think it's more a case of "why not". The carrier was designed a certain way for a reason, and cutting part of it off for no good reason just doesn't seem right.

Link Posted: 2/1/2006 1:47:58 PM EDT

Originally Posted By JPN:
The BATF considers possession of a semi-auto AR-15 rifle and M-16 trigger group components (hammer, disconnector, selector, and trigger) to be possession of an unregistered Class 3 weapon. The M-16 parts do not have to be installed in the AR-15, just in the possession of an individual who also possesses an otherwise legal AR-15.


The term you're looking for is "constructive intent." It means that there is the assumption that the owner of the AR obtained the FA parts with the intent to assemble them into an illegal machinegun. This depends on the assumption that one cannot accidentally stumble across all the FA parts, and seems to be the crux of the uncertainty about whether using an "M16 carrier" in a semiauto AR is or is not allowed. The only thing an M16-type carrier can do in an otherwise unmodified semiauto AR is slow down its cyclic rate, but there are apparently still some "it's possible when the sun and planets align and the moon is in the seventh house..." type zealots in the ATF's enforcement ranks that think spit and twist ties for plastic bags can constitute an illegal machinegun in certain circumstances.

With all else being equal, the safe thing to to to slow your action down would to be installing a heavier buffer and maybe also a tungsten weight in your AR15 carrier.
Link Posted: 2/1/2006 2:25:28 PM EDT

Originally Posted By GHPorter:
The term you're looking for is "constructive intent."



Constructive intent, possession, whatever, no longer exists since 5/19/86, when the law was changed.

Having the parts to go full-auto, is called having a machine gun per US Code:

26 U.S.C. Sec. 5845 (b) Machinegun – The term “machine gun” means any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The term shall also include the frame or receiver of any such weapon, any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun, and 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.
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