Attached File


Crappy pic of my latest...  a "quasi-XM4".  Colt upper, Bushmaster barrel from Gunparts Corp, repro N-1 stock and Anderson lower.

..,and yes, no delta ring in the photo.  Barrel wasn't torqued yet... just posing for the camera!  

So cool.

I put one together a few months ago.  Mine has an old DPMS 1/9 14.5 barrel and an unkown A2 upper.  I had Colt 6 hole skinny HGs but changed them over to an old BFPU 2003 KAC rail.  Mine shoots great at 100m.

Just need to get a set of skinny handguards now

Not correct for the XM4 clone

Leave it alone, looks good as it is. Plus, why spend the money when you can use it for more ammo?

I like it, makes me miss my A2 carbine. But I'll just keep my 604 upper build for time being cause I'm broke

I believe they are for the XM.
Picture near the bottom of the thread shows an early XM4 used by the Rangers in Somalia.

BHD Thread page 23

I've gone back and forth on the handguard issue... I've seen pics of both skinny and fat on XM4s.  Don't know if it was Uncle Sam or Colt who were playing "mix master" with parts at that time.
I went with fat... simply because they were what was in the spare parts bin. But I might be talked into some skinnies,  if I can find a reasonable deal on some.

Rangers were using several models, we think mostly 727s, and not XM4s. The XM4 project ultimately got funded by TACOM to replace the M3 submachine gun, not SF as a replacement for the various carbines in use. Rangers and SF were doing off the shelf buys from Colt, while the Army took on the M4 project later after the original idea stalled due to lack of funding.

I think that means, In other words: 727's were skinny and xm4's were fat.  But I'm not completely sure about that.  

You may be right.  I guess I don't know what the difference would be between an XM4 and a 727.  I thought XM4 was an A2 upper with a M203 step cut barrel, and A1 or A2 lower. A 727 was the same except procured from COTS funds.  Good news for OP.  You can use CAR, M4 or KAC rail HGs for a clone.  I have seen pics of all of them in use.

Exactly.  That is the picture that motivated me to find a beat up KAC rail to put on my 727/XM4.

You may be interested in these threads:

https://www.ar15.com/forums/ar-15/XM4_Carbine/123-663965/?

https://www.ar15.com/forums/ar-15/XM4_vs_727/127-675471/

To summarize the differences between the 727 and XM4

727 skinny handguards XM4 has M4 handguards
727 A1 style lower with auto FCG XM4 A2 style lower and 3 rd Burst
727 two position tube XM4 four position
727 old nut XM4 Castle nut

The R0727 was a cataloged product with generally fixed specs, though there was some variation between the specific parts used:

14.5" 1/7 twist barrel with A2 compensator
M16A2 Match Sights
Two-position Telescoping Stock
M16A2 pistol grip
XM177/Carbine handguards
S-1-F FCG (the R0729 was the S-1-3 variant)

What's important to note is that there was no specification in Colt's commercial offerings as to whether telescoping stocks were old-style aluminum or newer Fibrite, or whether the lower receiver forging was A1-style or improved (A2-style). At least some examples were also made with lightweight profile barrels, though most appear to have been built with one of the developmental XM4 barrel profiles, a "government"-style barrel that was heavier forward of the handguards, but compatible with USGI M203s.


The XM4 (R0720) was a developmental weapon that began using the M16A2 Carbine as a basis (something quite similar to the R0727) and proceeded from there to test, improve, and standardize the different parts--however, throughout the majority of the development process, there was no fixed configuration, it was a developmental weapon, and a variety of different parts were used, all of which would be stepping stones to the final M4 Carbine (R0920) specifications.

The double-heat shield handguards were one of the components that were developed and standardized during the XM4's development process, as was the final barrel profile, the four position receiver extension, castle nut, and feedramp angle.


The XM4 was not initially envisioned as a "commando" weapon, but rather as more of what we would now recognize as a "PDW" and designed initially to replace SMGs before ultimately being designated in the Carbine role as successor to the M3 Carbine (conveniently, the XM4 nomenclature could be retained, since the last SMG to be type-classified was the M3 as well). The Marine Corps was briefly interested in it for Force Reconnaissance, however it both originated as, and ultimately was concluded during its long developmental period (~10 years) by the Army.

Meanwhile, SOF units had continued to purchase and use COTS weapons to replace aging XM177-series weapons (the rise of the MP5 as a commando weapon in the 1970s and into the 80s took some of the attention off of M16-based "shorties," though this period was actually relatively short-lived relative to the place that the MP5 now occupies in the modern zeitgeist--the move back towards M16-based weapons started around the mid-1980s, right when all the action movies started making the MP5 "famous"). When the relatively newly formed Army CT organizations sought an M16-based weapon, they chose to purchase the R0723, while the majority of USSOCOM primarily procured R0727 models for the roles in which XM177-based weapons and R653s had been previously used (the Air Force was also off doing their own thing putting together random parts to make carbines/SMGs).  

Once the M4/M4A1 came online, there wasn't a need to purchase as many COTS weapons as they were now in the "mainstream" supply system, and the basis of issue included SOF (A1).

Also once the M4/M4A1 was standardized, Colt introduced new commercial models:

R0777/R0779--fixed carry handle M4 Carbine (M4/M16A2E), which began by using up R0727/723/etc. parts, then transitioned to using M4-spec parts

R0977/R0979--flattop M4 Carbine

The supposed "late" 727s that used M4 double heat shield handguards were most likely (it's impossible to say for sure without being able to check the receiver markings and/or POs) either later replacements/retrofits or R0777/779s that had been fitted with them from the factory.

~Augee

I <3 you Augee.

Thanks Augee.  Your knowledge and research is amazing and greatly valued.  Guess we can make our clones with either handguards or lowers.

I do have a pic of some sort of SF in Somalia with MP5's.  Or at least one guy.  And it looked like a patrol, not a pilot.  FWIW.  It's kind of a blurry pic though.........  I can see if I can dig it out.  You might know which one I'm talking about.

Better pic... Attached File

Glorious. Fat handguard just like right with that.  I like the skinny's on a 723

Heres a picture of the XM rollmark :)

Awesome!  I need to do an 80% and have it roll marked like that!