[natedog]

How is the M16A4 different from the A2?

[Badger Arms]

http://www.thehighroad.org/showthread.php?s=&threadid=9010&highlight=m16A4

[voilsb]

the basic (and as far as I remember, the only important one) difference is that the A4 has a detachable carry handle and integrated rail system, while the A2 does not. other than that, they're nearly identical.

[natedog]

what happened to the A3?

[voilsb]

the A3 is a full-auto version of the A2. I'm pretty sure it doesn't have the removeable handguard and rail system, but I wouldn't be too suprised if I was wrong about that.

edited to clarify

[Skunkabilly]

How much weight do one of those rail doodads add?

[Badger Arms]

This was just covered about a week or two ago:

M-16 -- Full-Auto, no forward assist, 1-12 Twist (Air Force Model)
M-16A1 -- Full-Auto, Forward Assist, (Vietnam Model)
M-16A2 -- Burst, New Sights, New Handguard, New Stock, 1-7 Twist
M-16A3 -- Full-Auto, Flat-top
M-16A4 -- Burst, Flat-top

The Rail doodad isn't a neccessity to the designation AFAIK.

[Ed]

M-4 is also shorter and has telescoping stock. "that is in comparison to stock issue M-16a2. I was in one of the first units issued M-4s back in 97, when they were rolled out to the masses and mine and others in my unit would do a 4 or 5 round burst. Had to get that fixed. I didn't see that again after a few months.

[Jeff White]

The A3 designation for a flattop upper receiver is something commercial AR15 manufacturers came up with. According to: Army TM 9-1005-319-23&P
Air Force TO 11 W3-5-5-42
Navy SW370-BU-MMI-010
dated May 1981 complete through change 7 dtd 1 Sep 2001

The M16A4 is the only rifle with the detachable carry handle. The M16A3 has the fixed carry handle just like the A2.

An M16A4 or M4A1 doesn't have to have the M4 or M5 Rail Adapter System to be considered a complete weapon. Both RAS's are considered accessories. I was unable to find a weight listed for the rail systems.

So we have the following M16 type weapons in US service:

M16 - 20" light weight 1/12 twist barrel, 3 prong flash hider, no forward assist.

M16A1 - basically the same as the M16 with the addition of the birdcage type flash hider and the forward assist.

M16A2 - 20" 1/7 twist barrel that is heavy from the front sight base forward, new furniture that includes round handguards, 5/8" longer buttstock, pistol grip with finger swell, forward assist button changed from teardrop to round. Fire control changed to safe-semi-burst. Rear sights adjustable for both windage and elevation. Front sight post changed from round to square. Flash hider had bottom slots filled to minimize dust signature when firing from the prone.

M16A3 - same as the M16A2 except fire control changed back to safe-semi-auto.

M16A4 - same as M16A2 except upper receiver is flattop design and removable carry handle sights only are adjustable to 600 meters.

M4 - Carbine version of the M16A2. 14.5" 1/7 twist barrel, heavy in front of the front sight with a groove milled into it to allow attachment of the M203 grenade launcher. Safe-semi-burst fire control. Flattop upper with removeable carry handle. 4 position collapsible buttstock.

M4A1 - Same as the M4 except for the fire control which is safe-semi-auto. New production M4A1s have a new heavy barrel.

You will find M16A1s in service with the reserve components that have various A2 parts installed. After the Army adopted the M16A2 in 1985, it stopped production of the repair parts for the M16A1 that could be used on both weapons. So there are a lot of M16A1s out there sporting A2 furniture, flashiders and front sight posts.

The M16A4 and M4A1 are usually issued the the rail adapter system.

The first M4s had fixed carry handle upper receivers. I don't know how many of these may still be in service. The change to the removeable carry handle was accomplished before large scale fielding occurred in 1998.

Jeff

[Skunkabilly]

So, for the civilian, there's not much difference between the A3s and A4s?

If I get this here Colt with detachable carry handle, will it be pretty much the same thing?

http://www.colt.com/colt/assets/images/a2f16_m16a2.gif

[UnknownSailor]

The A3s in my armory are all A1's with A2 uppers. Kinda weird seeing "M-16A1" stamped on there, with the A2 upper. They have the A2 stock and grip, but are otherwise A1 lowers.

[Jim K]

Technically, the M4 is not a rifle, it is a carbine, which is why it is the M4. The previous carbines in the series were the .30 carbines of WWII vintage, the M1, M2 (selective fire), and M3 (infrared sights). Hence, M4 for the new carbine.

The M4 carbine should not be confused with the M16A4, which, as noted above, is the latest variation of the M16.

Jim