M4 vs M4A1

[jford1]

Is the M4A1 replacing the M4 or is it for SOCOM only? Are the new M4s eventually going to have the heavier barrel and H3 buffer? I know that the M4A1 is full auto rather than burst but are the barrel and buffer going to be added to the current issue M4s? Are there any other differences besides the fire rate, barrel profile, and buffer? What type washer (crush/peel) does the current production M4 use? I’m going to build a CMMG or Stag clone and I’m trying to decide between the standard and A1 configuration. I’m not really concerned with the benefit from a heavy barrel in a semi but which version is being purchased by the military currently.

 

[Chipperman]

Here is some info I swiped from ARF.com. It does not have all that you are asking for.

M4
In 1994, the U.S. Army officially adopted its second carbine of the 20th century. Though carbine versions of the M16 had been used all along (as the XM177 as well as the CAR-15), demand for these was limited to select groups. With the increase in the use of Special Operations forces during and after the Cold War, the demand for a shorter, lightweight weapon was increased.

The M4 was developed by Colt's Manufacturing Company, and is intended to be used by Special Operations forces as well as other select members of the military. It is designed to replace a variety of carbines and SMGs in the Army's arsenal, as well as to repeat the accuracy and reliability of the M16A2. It uses a 14.5" barrel, and a four-position telescoping stock while maintaining the ability to mount an M203 grenade launcher. In the collapsed position, it measures under 30 inches, and weights just over 5 1/2 pounds, with an effective range of 600 meters. The M4 is available with 3-shot bursts (M4) as well as full-auto capabilities (M4A1).

Both versions of the M4 are equipped with a Picatinny-Weaver Rail system to replace the carry handle. This allows for a variety of sighting systems to be mounted atop the receiver, from the standard handle with A2 sights to night-vision devices, scopes, and lasers.

Current military inventory includes:

Rifle Sights Twist Selector Bbl Issue
M16A1 Handle 1:12 AUTO 20" Std B
M16A2 Handle 1:7 BURST 20" Std A
M16A3 Handle 1:7 AUTO 20" Limited issue
M16A4 Flattop 1:7 BURST 20" Limited issue
M4 Flattop 1:7 BURST 14.5" Std A
M4A1 Flattop 1:7 AUTO 14.5" Std A

Here's my understanding of your specific questions:

Is the M4A1 replacing the M4 or is it for SOCOM only? Limited use, but not just to SOCOM
Are the new M4s eventually going to have the heavier barrel and H3 buffer? Not sure
I know that the M4A1 is full auto rather than burst but are the barrel and buffer going to be added to the current issue M4s? I doubt it

 

[jford1]

Thanks! So they will probably only issue the heavy barrel and buffer for full auto guns, which makes sense. What other groups use the A1 version? Is it just special teams or are some infantry (army or marines) getting them? It is interesting to me that the military is going back to full auto capable assault rifles even if it is in small numbers. I wonder what the ratio of M4s to M4A1s is and what is projected. Is the A1 supposed to better fill the sub-gun role that a three round burst M4 can’t?