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Archived [ARCHIVED THREAD] - Dumb question with probably a simple answer.
Posted: 3/8/2006 4:27:33 PM EDT
What's the difference between an AR15/M4/M16 etc

I get asked this by friends alot when I call my gun an M4(gery).

I just figured it was the civilian version.  Is there such thing as an automatic AR-15?

What makes a barrel M4 profile, as opposed to an M16?

Link Posted: 3/8/2006 4:32:14 PM EDT
[#1]
Quoted:
Is there such thing as an automatic AR-15?


I guess if you owned an AR-15, and got the tax stamp and purchased a RDIAS, you would have a fully automatic AR-15



Other than that, I think your intuition is correct.  M4 and the variants of the M16 are military, select-fire rifles, and the various AR-15 derivatives are generally the "civilian" semi-auto versions.
Link Posted: 3/8/2006 4:33:13 PM EDT
[#2]
Quoted:
Quoted:
Is there such thing as an automatic AR-15?


I guess if you owned an AR-15, and got the tax stamp and purchased a RDIAS, you would have a fully automatic AR-15



Haha.  I'm just talking about production wise.

AR-15's were designed to be semi-automatic civilian weapons correct?

ETA: Saw your edit

Link Posted: 3/8/2006 4:34:38 PM EDT
[#3]
Quoted:

AR-15's were designed to be semi-automatic civilian weapons correct?

ETA: Saw your edit


For much more information, click on the "Information" tab to the upper right, and check out some of the articles about the AR-15.  

I think a lot of your answers will be in there.
Link Posted: 3/8/2006 4:40:33 PM EDT
[#4]
Quoted:
Quoted:

AR-15's were designed to be semi-automatic civilian weapons correct?

ETA: Saw your edit


For much more information, click on the "Information" tab to the upper right, and check out some of the articles about the AR-15.  

I think a lot of your answers will be in there.


Interesting.  So the AR15 was the original rifle that the military adopted and then called it the M16?

Link Posted: 3/8/2006 4:48:12 PM EDT
[#5]
pretty much..im sure you have noticed that all the firearms the military adopts gets a M in the title M249 , m60, mk19, m40a1, m16, m14..etc... m4 profile barrel is m4 profile barrel because it has a cut out to mount the m203 40mm grenade launcher where as a standard m16 does not. m4 is carbine and m16 is rifle.

Link Posted: 3/8/2006 4:49:44 PM EDT
[#6]
Quoted:
Quoted:
Quoted:

AR-15's were designed to be semi-automatic civilian weapons correct?

ETA: Saw your edit


For much more information, click on the "Information" tab to the upper right, and check out some of the articles about the AR-15.  

I think a lot of your answers will be in there.


Interesting.  So the AR15 was the original rifle that the military adopted and then called it the M16?


Yep.
Link Posted: 3/8/2006 5:11:08 PM EDT
[#7]
Quoted:
pretty much..im sure you have noticed that all the firearms the military adopts gets a M in the title M249 , m60, mk19, m40a1, m16, m14..etc... m4 profile barrel is m4 profile barrel because it has a cut out to mount the m203 40mm grenade launcher where as a standard m16 does not. m4 is carbine and m16 is rifle.


Yeah that's pretty obvious.  You never hear much about the previous names of these firearms though, unlike the AR-15.  Like what actually is the M40A1?  I just look at it as the military's hardcore sniper rifle haha

Link Posted: 3/8/2006 5:42:16 PM EDT
[#8]
Quoted:
Quoted:
pretty much..im sure you have noticed that all the firearms the military adopts gets a M in the title M249 , m60, mk19, m40a1, m16, m14..etc... m4 profile barrel is m4 profile barrel because it has a cut out to mount the m203 40mm grenade launcher where as a standard m16 does not. m4 is carbine and m16 is rifle.


Yeah that's pretty obvious.  You never hear much about the previous names of these firearms though, unlike the AR-15.  Like what actually is the M40A1?  I just look at it as the military's USMC's hardcore sniper rifle haha


M40A1
Link Posted: 3/8/2006 6:23:48 PM EDT
[#9]
Quoted:
Quoted:
Quoted:
pretty much..im sure you have noticed that all the firearms the military adopts gets a M in the title M249 , m60, mk19, m40a1, m16, m14..etc... m4 profile barrel is m4 profile barrel because it has a cut out to mount the m203 40mm grenade launcher where as a standard m16 does not. m4 is carbine and m16 is rifle.


Yeah that's pretty obvious.  You never hear much about the previous names of these firearms though, unlike the AR-15.  Like what actually is the M40A1?  I just look at it as the military's USMC's hardcore sniper rifle haha


M40A1


Thanks :)

Link Posted: 3/8/2006 8:39:53 PM EDT
[#10]
An AR-15 is a family of weapons of which the M16 and M4 are apart of.

Link Posted: 3/9/2006 6:55:30 AM EDT
[#11]
Quoted:
Quoted:
pretty much..im sure you have noticed that all the firearms the military adopts gets a M in the title M249 , m60, mk19, m40a1, m16, m14..etc... m4 profile barrel is m4 profile barrel because it has a cut out to mount the m203 40mm grenade launcher where as a standard m16 does not. m4 is carbine and m16 is rifle.


Yeah that's pretty obvious.  You never hear much about the previous names of these firearms though, unlike the AR-15.  Like what actually is the M40A1?  I just look at it as the military's hardcore sniper rifle haha


A few original names:
M240 = FN MAG 58
M249 = FN Minimi
M24 = Remingon 700
M21 = M14 = military from the get-go
M9 = Beretta 92FS
M8 = Sig Sauer P226

Obviously that's just a starter list

Link Posted: 3/9/2006 7:21:34 AM EDT
[#12]
Quoted:
What makes a barrel M4 profile, as opposed to an M16?


Length, How it's profiled, the barrel extension (in particular the feed ramps), front sight base.

The M16 & M16A1 used a thin 0.60" 20" long barrel that tapered down to about .58" near the muzzle, with a 1:12 twist.

The M16A2, M16A3, and M16A4 use a barrel that was roughtly the same thickness under the barrel (0.64") but from the front sight base forward it was about 0.74".  Forcing a change in the FSB (needed larger holes for the barrel.  Twist was tightned to 1:7.

M4 barrels were the same profile as the M16A2 barrels with some changes.  First the length was only 14.5", second a notch was cut forward of the front sight base (at 0.64" dia) to allow for the attachment of an M203.  The receiver extension was modified with steeper feed ramps, and the front sight base was milled a little different so the front sight pin ended up being installed 0.04" higher.

Then of course are the M4A1 barrels - a 4oz heavier version of the M4 barrel that is thicker under the handguards (still no civie HBAR thickness) with side notches cut to still allow attachment of an M203.
Link Posted: 3/9/2006 7:39:09 AM EDT
[#13]
Quoted:
Quoted:
What makes a barrel M4 profile, as opposed to an M16?


Length, How it's profiled, the barrel extension (in particular the feed ramps), front sight base.

The M16 & M16A1 used a thin 0.60" 20" long barrel that tapered down to about .58" near the muzzle, with a 1:12 twist.

The M16A2, M16A3, and M16A4 use a barrel that was roughtly the same thickness under the barrel (0.64") but from the front sight base forward it was about 0.74".  Forcing a change in the FSB (needed larger holes for the barrel.  Twist was tightned to 1:7.

M4 barrels were the same profile as the M16A2 barrels with some changes.  First the length was only 14.5", second a notch was cut forward of the front sight base (at 0.64" dia) to allow for the attachment of an M203.  The receiver extension was modified with steeper feed ramps, and the front sight base was milled a little different so the front sight pin ended up being installed 0.04" higher.

Then of course are the M4A1 barrels - a 4oz heavier version of the M4 barrel that is thicker under the handguards (still no civie HBAR thickness) with side notches cut to still allow attachment of an M203.


Better check that again.

Link Posted: 3/9/2006 7:41:20 AM EDT
[#14]
Quoted:
Better check that again.

??  Clarification please, I can't check again till I get home.  But IIRC my Colt M4 barrel is milled a bit different on the height.
Link Posted: 3/9/2006 7:41:49 AM EDT
[#15]
Quoted:
Quoted:
Better check that again.

??  Clarification please, I can't check again till I get home.  But IIRC my Colt M4 barrels are milled a bit different on the height.



The higher FSB is on flattops, not carbines

Link Posted: 3/9/2006 7:42:41 AM EDT
[#16]
The M16A2 does not use the same barrel assembly as a M16A4.

Link Posted: 3/9/2006 7:43:26 AM EDT
[#17]
Quoted:
The higher FSB is on flattops, not carbines


Last time I checked M4s are flattops, other than a very small batch at the begining of the contract.
Link Posted: 3/9/2006 7:44:03 AM EDT
[#18]
Quoted:
The M16A2 does not use the same barrel assembly as a M16A4.


You are correct, I should have verified in the -23&P first.  Thanks for the correction.
Link Posted: 3/9/2006 7:44:38 AM EDT
[#19]
Quoted:
Quoted:
The higher FSB is on flattops, not carbines


Last time I checked M4s are flattops


And so are M16A4s.  The higher FSB is not specific to carbines.

It specific to anything that has a flattop.

To say it is an M4 feature is not correct.

Link Posted: 3/9/2006 7:59:41 AM EDT
[#20]
Quoted:
...To say it is an M4 feature is not correct.


I look at it AS a feature of M4 barrels, and I look at it AS a feature of M16A4 barrels.  Two very different barrels that share a feature.
Link Posted: 3/9/2006 8:44:23 AM EDT
[#21]
Quoted:
Quoted:
The higher FSB is on flattops, not carbines


Last time I checked M4s are flattops, other than a very small batch at the begining of the contract.



If you want to get technical, that is not true either. The M4 Carbine has a fixed-handle A2 upper. The M4A1 is the flattop.
Link Posted: 3/9/2006 8:59:52 AM EDT
[#22]
Quoted:
Quoted:
The M16A2 does not use the same barrel assembly as a M16A4.


You are correct, I should have verified in the -23&P first.  Thanks for the correction.


What's the difference? I assume that the FSB, right? Other than the FSB the actual barrel is the same, isn't it?
Link Posted: 3/9/2006 9:01:48 AM EDT
[#23]
Quoted:

If you want to get technical, that is not true either. The M4 Carbine has a fixed-handle A2 upper. The M4A1 is the flattop.



That is incorrect.

M4 carbines are flattops with safe-semi-burst FCG.  Again only small amount were delivered with the fixed handle.

M4A1s carbines are flattops with safe-semi-auto FCG.  Most also now have the heavier barrels as well.
Link Posted: 3/9/2006 9:02:57 AM EDT
[#24]
Quoted:
Other than the FSB the actual barrel is the same, isn't it?

The barrel profile is definately the same.  I don't know if the M16A4 uses the extended feed ramps.  Perhaps Ryan or Ekie (our resident Colt experts) could chime in.
Link Posted: 3/9/2006 9:54:38 AM EDT
[#25]
Quoted:
Quoted:
Other than the FSB the actual barrel is the same, isn't it?

The barrel profile is definately the same.  I don't know if the M16A4 uses the extended feed ramps.  Perhaps Ryan or Ekie (our resident Colt experts) could chime in.


Extended feedramps are not suppose to be on rifles.  They rarely appear on Colt commerical rifles and are not on any USGI rifles.

Link Posted: 3/9/2006 9:55:10 AM EDT
[#26]
Quoted:



If you want to get technical, that is not true either. The M4 Carbine has a fixed-handle A2 upper. The M4A1 is the flattop.



This is wrong

Link Posted: 3/9/2006 9:56:26 AM EDT
[#27]
Quoted:
Quoted:
...To say it is an M4 feature is not correct.


I look at it AS a feature of M4 barrels, and I look at it AS a feature of M16A4 barrels.  Two very different barrels that share a feature.


Yes, but I would just refer to it as a feature of a flattop gun as it extends to all flattops(ie 6920, 6721, M4, M16A4, etc)

If you refer to it as a feature of an M4, then people think it applies to M4 only and we have to go through 5 page threads to get the correct info.

Link Posted: 3/9/2006 11:12:28 AM EDT
[#28]
Quoted:
If you refer to it as a feature of an M4, then people think it applies to M4 only and we have to go through 5 page threads to get the correct info.


That is probably true,  but I'm not responsible for what other think or infer.
Link Posted: 3/9/2006 8:55:00 PM EDT
[#29]
Quoted:
Quoted:

If you want to get technical, that is not true either. The M4 Carbine has a fixed-handle A2 upper. The M4A1 is the flattop.



That is incorrect.

M4 carbines are flattops with safe-semi-burst FCG.  Again only small amount were delivered with the fixed handle.

M4A1s carbines are flattops with safe-semi-auto FCG.  Most also now have the heavier barrels as well.



I have been issued both. I have received training on both, including nomenclature/features of each model (US Army). All the "M4 Carbines" I have ever seen had A2 uppers. All of the M4A1's I have seen had flattop uppers.  You are correct on the FCG variations. I will retract my statement of "you are incorrect"; but could you list a source for this (other than wikipedia please) as I have never seen a flattop marked "M4."
Link Posted: 3/10/2006 7:52:57 AM EDT
[#30]
Quoted:
Quoted:
Quoted:

If you want to get technical, that is not true either. The M4 Carbine has a fixed-handle A2 upper. The M4A1 is the flattop.



That is incorrect.

M4 carbines are flattops with safe-semi-burst FCG.  Again only small amount were delivered with the fixed handle.

M4A1s carbines are flattops with safe-semi-auto FCG.  Most also now have the heavier barrels as well.



I have been issued both. I have received training on both, including nomenclature/features of each model (US Army). All the "M4 Carbines" I have ever seen had A2 uppers. All of the M4A1's I have seen had flattop uppers.  You are correct on the FCG variations. I will retract my statement of "you are incorrect"; but could you list a source for this (other than wikipedia please) as I have never seen a flattop marked "M4."


Sources:

The Black Rifle II
Myself
Ekie
Colt
Capt Richardson
Pictures of US mil in Iraq
SAW

Link Posted: 3/10/2006 8:10:41 AM EDT
[#31]
Quoted:
Quoted:
Quoted:
Quoted:

If you want to get technical, that is not true either. The M4 Carbine has a fixed-handle A2 upper. The M4A1 is the flattop.



That is incorrect.

M4 carbines are flattops with safe-semi-burst FCG.  Again only small amount were delivered with the fixed handle.

M4A1s carbines are flattops with safe-semi-auto FCG.  Most also now have the heavier barrels as well.



I have been issued both. I have received training on both, including nomenclature/features of each model (US Army). All the "M4 Carbines" I have ever seen had A2 uppers. All of the M4A1's I have seen had flattop uppers.  You are correct on the FCG variations. I will retract my statement of "you are incorrect"; but could you list a source for this (other than wikipedia please) as I have never seen a flattop marked "M4."


Sources:

The Black Rifle II
Myself
Ekie
Colt
Capt Richardson
Pictures of US mil in Iraq


Add to them:
TM 9-1005-319-23&P
PS Magazine PS529 Dec 1996
PS Magazine PS573 Aug 2000

For those who have never served, PS Magazine is a publication put out by the US Army on preventative maintenance and repair issues for issued equipment.  It is in comic book format.


Note the above photo is taken from the US Army's Rock Island Arsenal site (there is a description there as well but it doesn't get that deep into detail)

www.army.mil/fact_files_site/m-4_carbine/index.html  A little something from the Army's 'Fact File' (note the flattop).
Archived [ARCHIVED THREAD] - Dumb question with probably a simple answer.
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