AR/M16/M4 types?

[Carl]

I'm pretty new to these kind of rifles. I see them and I hear different names like AR-15, M-16, M4, etc... and I really don't know the difference. They mostly look identical except for a few differences like adjustable stock and maybe a different muzzle flash hider. Someone clue me in.

 

[C-grunt]

M16/AR15 (rifle) have a 20'' barrel and fixed stock.

M4s actually have a 14.5" barrel but for the carbine AR15s its usually 16" unless you wanna pay the tax stamp for the short barreled rifle (sbr). They also come with a collapsible stock.

This is the standard basics but since the AR15 is so modular its easily changed to how you want it and come in many configurations from the factory.

Also if it is an A2 it has the fixed carry handle sights, but the A3/A4s have a flat top.

 

[Carl]

What about all the A1, A2, whatever that sometimes follows. Do they have anything to do with the full auto military types and the semi-auto civilian types?

 

[LoneRider]

The M16A1 is the original militarized AR-15, issued in the Vietnam War and had full auto capability.

The M16A2 was a modification of the A1 insomuch that the full auto capability was removed and the three-round burst option was added since it was discovered soldiers were using their A1s as bullet hoses in firefights. I've heard accounts from a couple NCOs in my battalion of M16A1s being issued to Army National Guard Units (said NCO had been an 11B in the Colorado National Guard in 1986) well into the 1980s (can anyone verify this?).

I'm not sure about A3/A4 M16 other than the fact that they have the flattop rails and usually sport ACOG/M68 Aimpoint optical sights.

Look at the wikipedia article on the M16 as well.

 

[Jeff White]

Main identifying feature, there are more differences between the models then I listed

M16 = 20" barrel, full auto trigger group, sights that require a tool to adjust, no forward assist.

M16A1 = 20" barrel, full auto trigger group, sights that require a tool to adjust, forward assist.

M16A2 = 20" barrel that is heavy at the front, sights that you can adjust with your finger tips, stock 5/8" longer, 3 round burst trigger group, new flash hider that is closed at the bottom.

M16A3 = Identical to the M16A2 except has a full auto trigger group. Produced in limited quantity for the Navy.

M16A4 = basically an M16A2 with a flattop upper receiver and often found with the M5 RAS (rail adapter system)

M4 = 14.5" barrel, collapsible stock, 3 round burst trigger group. A very limited number were originally produced with a fixed carry handle upper but I doubt any are still in service. Flattop upper adopted before it was fielded in large numbers.

M4A1 = An M4 with a full auto trigger group.

You can't tell what model someone is using by the furniture and the round hand guards and longer buttstocks fit the M16 and M16A1 and the military stopped procuring the triangular hand guards and the shorter butt stocks when the M16A2 became standard.

There were still M16A1s in Guard and Reserve units when I retired in 2003. I wouldn't be surprised if there still weren't some out there.

 

[RockyMtnTactical]

Basically, an AR15 is a generic term use for all of the different AR variations. AR15 is a registered trademark of Colt, but the term is used to refer to all brands by most people.

Here is a pic of an M4 (the shorter one) and an M16A2.

http://3.bp.blogspot.com/_RYwUPr35r...1600-h/M4+carbine+and+M16A2+in+background.jpg

An M4 and an M16 are both AR15 variants.

 

[LoneRider]

Basically everyone carries the M4A1 in the Army these days, save for support guys who carry the M16A2.

There were still M16A1s in Guard and Reserve units when I retired in 2003. I wouldn't be surprised if there still weren't some out there.

I'd have figured they'd shifted the A2's into the Guard/Reserve since the regular Army is carrying the M4A1 (even the mechanics and cooks).

 

[C-grunt]

Not all of the Army is carrying M4s. A lot of the Mech units still have the A4s.

 

[zubair723]

Lot of M4A1s hitting my country's black markets via AFGHANISTAN

 

[Ned Kelly]

Is the twist rate on the A3

1 in 7

or

1 in 9?

My ar-15 a3 has a 1 in 9.

Just curious.

 

[Jeff White]

I'd have figured they'd shifted the A2's into the Guard/Reserve since the regular Army is carrying the M4A1 (even the mechanics and cooks).

The regular Army is not carrying M4A1s. The regular Army is carrying M4s and M16A4s and some M16A2s here and there. The M4A1 is only used by SOCOM units in the Army.

Is the twist rate on the A3

1 in 7

or

1 in 9?

M16 twist rate is 1 in 12
M16A1 twist rate is 1 in 12
M16A2, A3, A4, M4 and M4A1 all have a 1 in 7 twist rate. The 1 in 7 twist rate is necessary to stabilize the M856 tracer round which is a very long bullet to hold enough tracing compound to meet the specification fir trace before burnout.

 

[LoneRider]

I've seen M4A1s as general issue in Support Formations and line units, at least in the CAV where I'm presently assigned.

Heck, even our mechanics, supply clerks, and cooks are carrying M4s.

 

[Jeff White]

I've seen M4A1s as general issue in Support Formations and line units, at least in the CAV where I'm presently assigned.

M4A1s? With full auto trigger groups? I'm pretty surprised, but then I've been retired for 5 years now and my son is away from the real Army on recruiting duty.

 

[LoneRider]

I'm not joking. I've seen them issued to everyone. Only some of the real real "rear echelon" (term used loosely) folks carry 16A2/A3/A4 rifles.

 

[huckster]

Maybe there's quite a bit of unit to unit disparity. Last summer most of the 3rd ACR was carrying M4s not M4A1s.

 

[61chalk]

Had the M-16A1 in the early 80's...good info. on them Jeff White,
wonder were all the older M-16's are now? In storage, sold to foriegn countries, scrappped......?....They should convert them to semi-auto an let CMP sell them....an throw in some M-14's too!!!!

 

[highorder]

They should convert them to semi-auto an let CMP sell them....an throw in some M-14's too!!!!

...once a machinegun, always a machinegun...

 

[LoneRider]

Actually I was mistaken, only our JTACs (Joint Terminal Air Controllers) carry the M4A1, the rest of us have three round burst capability. I misidentifed the M4s in that case.

 

[sarduy]

dont forget the "M4gery"

civillian version of the M4

 

[RyanM]

Another slight difference is that the M16A1 had a pencil barrel (about 5/8" diameter) under the handguards and in front of the front sight. The M16A2 retained the pencil barrel under the handguards, but thickens to 3/4" ahead of the front sight. The later M16 variants and the M4 retain this. Earlier M4A1s also have this kind of barrel, but the newer ones will have about a 7/8" barrel under the handguards, for added heat resistance when doing multiple full magazine dumps.

 

[inherentical]

I've heard accounts from a couple NCOs in my battalion of M16A1s being issued to Army National Guard Units (said NCO had been an 11B in the Colorado National Guard in 1986) well into the 1980s (can anyone verify this?).

I don't know about the Army, but the Air Force had M16A1's that they were using at Aviano well into the 1990's.