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XM4 Clone/Information thread (Page 1 of 3)
Posted: 5/29/2019 1:01:40 PM EDT
[Last Edit: mech4matsnova][Edited]
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This thread is for the folks who are looking to clone the XM4 carbine. This thread is a work in progress and will be updated as more photos/info become available. If you have pics or info you would like to have added to the OP please IM/email me.
The XM4 program was started around 1985 at the behest of the USMC Recon units who were looking to replace their aging/worn out XM177s and M3s with a lightweight carbine length version of the standard issue M16A2(adopted by the USMC in 1983 as the standard rifle). Specs 
 Upper: A2, CM forge, 8/3 rear sight, A2 aperture(0-2), large round FA(early), small FA(later), A2 port door. Some early uppers are marked XM4 above the gas tube hole. 
Barrel Assembly: C MP 14.5" M4 profile, Chrome bore and chamber, A2 flash hider, peel washer(early) or crush washer(later), non F fsb w/A2 front sight post, standard delta ring, large diameter handguard 
BCG: FA profile, chrome key and carrier lining, phosphate exterior, c marked, MP bolt, standard charging handle 
Lower: 
A1 profile(early) or A2 profile(later), some marked XM4, others Colts M16A2, A2 grip. Theres some variation in the selector markings, some are marked "BURST", others are marked "AUTO". 
Stock/Buffer Tube: Colt N1 type, 2 or 4 position buffer tube, smooth lock nut(early) or locknut(later) 
Archived XM4 thread feat. coldblue and others involved in the A2 program 
Link to XM4 album courtesy of AmericanSheepdog XM4 album(36 images) Still from Colt 1993 promo, Rangers testing the XM4 
Img courtesy of coldblue, circa 1989 Attached File Colt M4 promo video, 1993  The ORIGINAL Colt M4 Carbine Video 1993 Foreign Users Israeli Border Police are currently issued XM4 style carbines 
Mexican Marines are issued XM4 carbines 
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One of Nortega's retards
ARF Callsign: Chord
ARF Callsign: Chord
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http://chestercountyarmory.com/products/?prodID=126
This linked transferable M16A2 carbine has an early barrel profile. |
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Originally Posted By mech4matsnova: It almost is, almost. There are a couple differences, as shown above. 1-"M-16A2 carbine" 727 . "COTS" carbine 2-"XM4" with CM upper, "Property of US Govt marked, UNIQUE barrel profile. 3- "M4" with carry handle. Mythical "USGI" piece that is more or less the same as a standard USGI M4 but with an A2 upper. 4- Colt 777 "COTS" carbine from late 90s. Probably not purchased by the US Military, but still neat. |
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I purchased an Armalite ex-LEO upper assembly a few years ago, that has a lot of characteristics of both the 727 and XM4. I'm at work, so I can't post and pictures of it:
Upper Receiver: A2, AR forge, 8/3 rear sight, Meprolight A2 aperture (0-2), small round FA, A2 port door. Barrel Assembly: Unmarked 14.5” M4 profile with A2X flash hider (pinned and welded), chrome bore and chamber, non-F FSB with Meprolight A2 post, standard delta ring, skinny 7-hole handguards, and standard sling loop below FSB. I added a Toolcraft and MPF BCG and standard charging handle later. I don’t know if Armalite was trying to capitalize on Colt’s marketing, by offering a similar but cheaper rifle. |
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Originally Posted By USGI: Well, if you want to be technical, I would argue that there are 4 major "models" that could be done as builds... Ignoring of course, local mods, minor parts changes, fire control changes that cause a new model number, Rifles that are in 727 configuration, but with older lowers, etc.... 1-"M-16A2 carbine" 727 . "COTS" carbine 2-"XM4" with CM upper, "Property of US Govt marked, UNIQUE barrel profile. 3- "M4" with carry handle. Mythical "USGI" piece that is more or less the same as a standard USGI M4 but with an A2 upper. Non F marked FSB on an M4 profile barrel. 4- Colt 777 "COTS" carbine from late 90s. Probably not purchased by the US Military, but still neat. |
"No clause in the Constitution could by any rule of construction be conceived to give to congress a power to disarm the people." William Rawle
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So, then there's THIS particular barrel that was sold by Fidelis I guess a few years back, to add to the potential barrel profiles to be mimic'd for XM4 builds.
Really it seems going the lengths of getting the lower engravings done and one of the prototype barrel profiles would be what sets a true XM4 build apart. Perhaps some place like Green Mountain could be convinced to do some runs of some of the above profiles? |
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Originally Posted By lancecriminal86:
So, then there's THIS particular barrel that was sold by Fidelis I guess a few years back, to add to the potential barrel profiles to be mimic'd for XM4 builds. Really it seems going the lengths of getting the lower engravings done and one of the prototype barrel profiles would be what sets a true XM4 build apart. Perhaps some place like Green Mountain could be convinced to do some runs of some of the above profiles? Also boo on this thread, now y’all got more wheels spinning in my head. 
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-Only two defining forces have ever offered to die for you, Jesus Christ and the American G.I. ~ One died for your soul, the other for your freedom.
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Originally Posted By HenryKnoxFineBooks:
Originally Posted By HenryKnoxFineBooks:
Originally Posted By USGI: Well, if you want to be technical, I would argue that there are 4 major "models" that could be done as builds... Ignoring of course, local mods, minor parts changes, fire control changes that cause a new model number, Rifles that are in 727 configuration, but with older lowers, etc.... 1-"M-16A2 carbine" 727 . "COTS" carbine 2-"XM4" with CM upper, "Property of US Govt marked, UNIQUE barrel profile. 3- "M4" with carry handle. Mythical "USGI" piece that is more or less the same as a standard USGI M4 but with an A2 upper. Non F marked FSB on an M4 profile barrel. 4- Colt 777 "COTS" carbine from late 90s. Probably not purchased by the US Military, but still neat. Even the 777 barrels, despite being late 90s/2000s production have non F marked FSB. |
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Originally Posted By lancecriminal86:
So, then there's THIS particular barrel that was sold by Fidelis I guess a few years back, to add to the potential barrel profiles to be mimic'd for XM4 builds. Really it seems going the lengths of getting the lower engravings done and one of the prototype barrel profiles would be what sets a true XM4 build apart. Perhaps some place like Green Mountain could be convinced to do some runs of some of the above profiles? Experimental/limited production at Colt? Sure. But "Property of US Gov't" XM4? No. |
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Originally Posted By USGI:
Not saying that is not a legit barrel, but that goes outside the "XM4" experiment standard if that makes sense. Experimental/limited production at Colt? Sure. But "Property of US Gov't" XM4? No. Originally Posted By USGI:
Originally Posted By lancecriminal86:
So, then there's THIS particular barrel that was sold by Fidelis I guess a few years back, to add to the potential barrel profiles to be mimic'd for XM4 builds. Really it seems going the lengths of getting the lower engravings done and one of the prototype barrel profiles would be what sets a true XM4 build apart. Perhaps some place like Green Mountain could be convinced to do some runs of some of the above profiles? Experimental/limited production at Colt? Sure. But "Property of US Gov't" XM4? No. Might be worth asking @coldblue if there's any info from the USMC period or perhaps if this was after the Marine's ran out of funding to support it. |
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Originally Posted By lancecriminal86:
So, then there's THIS particular barrel that was sold by Fidelis I guess a few years back, to add to the potential barrel profiles to be mimic'd for XM4 builds. Really it seems going the lengths of getting the lower engravings done and one of the prototype barrel profiles would be what sets a true XM4 build apart. Perhaps some place like Green Mountain could be convinced to do some runs of some of the above profiles? |
One of Nortega's retards
ARF Callsign: Chord
ARF Callsign: Chord
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Originally Posted By lancecriminal86:
So, then there's THIS particular barrel that was sold by Fidelis I guess a few years back, to add to the potential barrel profiles to be mimic'd for XM4 builds. Really it seems going the lengths of getting the lower engravings done and one of the prototype barrel profiles would be what sets a true XM4 build apart. Perhaps some place like Green Mountain could be convinced to do some runs of some of the above profiles? http://fidelisfirearms.com/2011/01/03/colt-m4-a2-14-5-fixed-carryhandle-upper/ 
Or maybe I should have bought one of these instead. http://fidelisfirearms.com/2011/03/10/colt-14-5-lightweight-723-m16-a2-complete-upper-895/ 
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| Colt XM4 SN 6153635 from my thread in the retro forum. Thought this would be useful here. |
"History does not long entrust the care of freedom to the weak or the timid"
"A people that values its privileges above its principles soon loses both"
"A people that values its privileges above its principles soon loses both"
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Originally Posted By JBecker_72:
Dang, I was hoping someone had something complete and ready to go. Guess it's not retro enough yet for that. Originally Posted By JBecker_72:
Originally Posted By mech4matsnova: Scour the internet(EE) and build it. |
One of Nortega's retards
ARF Callsign: Chord
ARF Callsign: Chord
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Originally Posted By AmericanSheepDog:
Colt XM4 SN 6153635 from my thread in the retro forum. Thought this would be useful here. This is where many of the M4 features come into being - 4 position stock, "fat" HGs, barrel with cuts for the M203, M4 feedramps, to support what becomes the M4A1 for SF use. The date on the build of 6153635 would be interesting in order to help ID when the D FA went to the current small round, and progress of=n feedramps. My C-M upper has feedramps on my XM4 build, but I also have a dark gray Colt Cerro upper with feedramps that is marked 4 over the gas tube opening, which is one reason why I'm in the camp of those who think there was the initial shipment of fixed handle M4s. OTOH, my dark gray C-AF flat top upper for the similar time frame M4A1 is M4 marked..... and so we are at the period in time where the F marked FSB appears. |
"No clause in the Constitution could by any rule of construction be conceived to give to congress a power to disarm the people." William Rawle
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Originally Posted By HenryKnoxFineBooks: Very useful - a few comments until coldblue happens by to offer more insight. IIRC from those who were there at the time, The XM4 project starts as a follow on from the M16A2, thus the lower shares those characteristics, rather than the A1 lower and AUTO from the 727 used by SF. Other parts such as barrel, HGs, stock are parts just lying around from previous production. The program stops due to lack of funding. The program resumes in the early 1990s under Army sponsorship, TACOM looking for a replacement for the M# for armor crews, etc. This is where many of the M4 features come into being - 4 position stock, "fat" HGs, barrel with cuts for the M203, M4 feedramps, to support what becomes the M4A1 for SF use. The date on the build of 6153635 would be interesting in order to help ID when the D FA went to the current small round, and progress of=n feedramps. My C-M upper has feedramps on my XM4 build, but I also have a dark gray Colt Cerro upper with feedramps that is marked 4 over the gas tube opening, which is one reason why I'm in the camp of those who think there was the initial shipment of fixed handle M4s. OTOH, my dark gray C-AF flat top upper for the similar time frame M4A1 is M4 marked..... and so we are at the period in time where the F marked FSB appears. Just a shot in the dark, but if the XM4 used the same serial number block as USGI Colt M-16A2s, then the 615xxxx serial number is pretty early. My issued M-16A2 from 95-98 was 6213499, and it had a large D, grey, etc. M4A1s were issued in 1995. The "White side" SF I supported for Bosnia in December 1995 had just gotten them. Hadn't even properly zeroed them. The first "M4" issued to conventional forces, I saw was late 1997, and it was a curiosity then. Summer of 1997, I did a large mixed expercise with guys from all over Ft.Bragg. Nobody had any sort of short carbines, with the exception of the "Group" support guys. Even the 18th Airborne Corp LRS (guys in the 1993 Colt demo video) were rockin M-16A2s. |
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Originally Posted By AmericanSheepDog:
Colt XM4 SN 6153635 from my thread in the retro forum. Thought this would be useful here. |
If U can't Truck It F!@k It!
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Originally Posted By imdBman:
Thanks for posting that! Thank You COLDBLUE, for your contributions. Amazing how similar the barrel profile looks compared to a Colt Canada C8A3 15.8". Originally Posted By imdBman:
Originally Posted By AmericanSheepDog:
Colt XM4 SN 6153635 from my thread in the retro forum. Thought this would be useful here. Updated OP with new pics and new Foreign Users section |
One of Nortega's retards
ARF Callsign: Chord
ARF Callsign: Chord
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Originally Posted By mech4matsnova: Special thanks to @coldblue @AmericanSheepDog @USGI and all others who have contributed so far. Updated OP with new pics and new Foreign Users section |
"History does not long entrust the care of freedom to the weak or the timid"
"A people that values its privileges above its principles soon loses both"
"A people that values its privileges above its principles soon loses both"
| @coldblue would you be interested in helping me write a report for the West Point Museum on the rifle I photographed? |
"History does not long entrust the care of freedom to the weak or the timid"
"A people that values its privileges above its principles soon loses both"
"A people that values its privileges above its principles soon loses both"
|
The XM4 on display at the National Infantry Museum, Fort Benning, GA. SN 6153641
Attached File Courtesy National Infantry Museum Collection, United States Army Attached File Courtesy National Infantry Museum Collection, United States Army Attached File Courtesy National Infantry Museum Collection, United States Army |
"History does not long entrust the care of freedom to the weak or the timid"
"A people that values its privileges above its principles soon loses both"
"A people that values its privileges above its principles soon loses both"
|
Originally Posted By AmericanSheepDog:
The XM4 on display at the National Infantry Museum, Fort Benning, GA. SN 6153641 https://www.AR15.Com/media/mediaFiles/463351/4A8D8463-5540-4B4A-90FC-5A9843715834_jpeg-1069232.JPG Courtesy National Infantry Museum Collection, United States Army https://www.AR15.Com/media/mediaFiles/463351/EBBA6DD5-1A74-409E-8693-519E58A578C1_jpeg-1069233.JPG Courtesy National Infantry Museum Collection, United States Army https://www.AR15.Com/media/mediaFiles/463351/66F025F4-73DC-4354-8EEC-915BA8E5DFFF_jpeg-1069234.JPG Courtesy National Infantry Museum Collection, United States Army |
"All welchers should be removed from the EE"-Aimless
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details please?
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Drain the swamp, lock her up, great awakening, trust the plan, 40,000 foot view, we have it all, nothing can stop what is coming.
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Originally Posted By togadelic:
details please? Originally Posted By togadelic:
80 lower, Colt guts Colt FA carrier, MPI bolt 16" 1-7 C MP bbl N Stock 4 pos buffer tube Surplus side swivel(FSB) I plan to take the bbl down and over to my machinist buddy so he can turn it down to the correct XM profile |
One of Nortega's retards
ARF Callsign: Chord
ARF Callsign: Chord
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I've mentioned it before, but my Marine buddy was carrying some kind of carbine in Africa in the late 90's.
Haven't talked to him in a bit, so I'm fuzzy on the details that he's probably fuzzy on. Possibly XM-4, or possibly a COTS? |
Married the most eligible woman on ARFCOM. https://www.ar15.com/forums/general/That-Every-Man-Be-Armed-Free-AR-parts-Please-contribute-your-parts-Trash-Panda-vid-Pg-15-/5-2146304/
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Originally Posted By mech4matsnova: Grey CM A2 upper(from EE) 80 lower, Colt guts Colt FA carrier, MPI bolt 16" 1-7 C MP bbl N Stock 4 pos buffer tube Surplus side swivel(FSB) I plan to take the bbl down and over to my machinist buddy so he can turn it down to the correct XM profile |
Drain the swamp, lock her up, great awakening, trust the plan, 40,000 foot view, we have it all, nothing can stop what is coming.
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Originally Posted By togadelic:
it is awesome Originally Posted By togadelic:
Originally Posted By mech4matsnova: Grey CM A2 upper(from EE) 80 lower, Colt guts Colt FA carrier, MPI bolt 16" 1-7 C MP bbl N Stock 4 pos buffer tube Surplus side swivel(FSB) I plan to take the bbl down and over to my machinist buddy so he can turn it down to the correct XM profile |
One of Nortega's retards
ARF Callsign: Chord
ARF Callsign: Chord
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Originally Posted By schaz42:
What is the correct XM4 barrel profile, how does it differ from an 727 barrel? William |
"No clause in the Constitution could by any rule of construction be conceived to give to congress a power to disarm the people." William Rawle
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The M4 program was initiated (IIRC) in 1983 by 9th ID (Army) as a Carbine version of the M16A2.
USMC took it over as an SMG replacement, before it reverted back to the Army as a Carbine. "Fortunately" it retained the "M4" designation throughout because the previous weapons in each class just happened to be both the M3 Carbine and M3A1 SMG. Near as I can tell, the "rumor" that the M4's barrel length was chosen for the ability to mount a bayonet comes from the Marine Corps' program--the 14.5" barrel length had existed since the R651 M16A1 "Carbine," and the more common R653, however when looking at SMG replacements, the Marine Corps looked at both the 11.5" "Commando" guns and the 14.5" variants, and ultimately opted to go with the 14.5" gun in part because it could accept a bayonet. The Colt 723 and 727 barrel profile is actually slightly different than the final M4 profile--the marking was a "(C)" instead of the "C," and the "ramp" at the rear of the M203 step where the barrel goes back up to .750 is shorter and and steeper on the (C) marked barrels versus the M4 barrel--in fact, many commercial "M4" profile barrels are more similar to the (C) barrel profile than the M4 profile. Again, as near as I can tell: The XM4 program was the R0720 and would have been marked PROPERTY U.S. GOVT/XM4. These would ONLY have been issued to and used by DoD units for operational testing, they would not have ever been sold commercial/export or even COTS by organizations within DoD, who had been doing so for years. Colt then began building commercial/export versions of the R0720, neverminding the BURST/AUTO variants and specific contract variants, the most commonly recognized ones are the R0723 with Field Sights -- AKA "A1 sights," while the R0727 had Match Sights -- AKA "A2 sights." These commercial/export guns were all marked "M16A2" in the commercial marking conventions, not the PROPERTY-style markings. These are the weapons that would have purchased COTS by both DoD and LE, etc., as well as FMS export weapons. Again, there were some different models with different contract variations, but they would have all come from this "family." Once the M4 was accepted and left the operational testing phase at some point it was determined that the M4 Carbine should have a detachable carry handle with accessory rail--once the M4 became a flattop, the model number became R0920--at the time "7xx" designated fixed carry handle, while the "9xx" designated a flattop receiver. Initially, the M4 Carbines would have gone to gaining units that by and large did not have a similar weapon that was being replaced--it was in many ways a wholly new weapon, and issued fairly sparingly to units that had a requirement for the Carbine. Obviously as GWOT came around years later, the M4 became the standard assault rifle, and now has been "replaced" yet again by the M4A1, but that brings us way out of the "A2 period." The S-1-F SOF variant of the M4 Carbine, the M4A1, which does not appear to have gone through an operational testing period and appears to have always been in a flattop configuration (there does not appear to be any indication I've yet found of "XM4E1" or "XM4A1" marked guns being produced, though you never know with Colt...) was designated the R0921. The M4A1 Carbines would have gone primarily to units within USSOCOM and other SOF proponents that already had COTS R072x-series weapons (usually mixed in with M16A2s), and M4A1s and R072x and even some R0777 (see below) would/could have all served along side each other during the mid-to-late 1990s when this transition was occurring. Simultaneously, when the XM4 became the M4, Colt appears to have shifted the R0723 and R0727 family under the umbrella of R0777, dropping the R072x family. These weapons were built with a mix of R072x family parts and M4 parts, and rollmarked "M4/M16A2E" in the commercial marking conventions. The earliest of these guns would have been almost indistinguishable from R0723s and R0727s, with "(C)" barrels, side-sling mounts, two position receiver extensions, lock nuts instead of castle nuts, single heat shield handguards, etc. Later guns would be almost indistinguishable from M4 Carbines--except have a fixed carry handle, using "C" marked M4 barrels, BUT with non-F marked FSBs, castle nuts, four position receiver extensions, etc., basically, Colt used up all their "old" parts, and then started using "new" parts--the R0777 was not discontinued by Colt well into the mid-2000s. Also when the M4 was adopted, Colt introduced the R0977, which was the commercial/export version of the M4A1 Carbine (flattop, S-1-F). As far as I can tell, Colt chose to keep the R0977 "pure," and did NOT use leftover 72x series parts, as the R0977 became their flagship product, and was supposed to "exactly" match the military issued M4 (again--more similar to the M4A1, but they continued to call it the "M4" only). The Israeli guns are actually primarily full-length M16A2s that were refurbished by the Israelis, who bought parts kits from Colt--they essentially re-barreled and re-stocked 20" guns. The Israelis of course are notorious for refurbishing, recycling, and even modifying M16A1s and M16A2s to suit their needs, which is why there have been plenty of "M16A1s" out there with M4 barrels as well, which would not be XM4s or R0723s or R0727s or GUU-5/Ps, as they've often been variously identified as, though the process by which they were "manufactured" is very similar to the GUU-5/P-family (for all intents and purposes, as Air Force 1/7 twist carbine... almost no other features are "standard"). The Israelis later also began purchasing complete flattop M4 uppers along with purchasing complete carbines that they would slap on whatever lower was available without concern for whether it was a commercial M16A1 or M16A2, or a "leased" PROPERTY marked gun. Almost all Colt FMS guns (like those used by the Mexican Marines) would not be M4s or XM4s, but some combination of R0727 or 725s (S-1-3 variant), or R0777s. Very few other countries would (at the time) have received PROPERTY marked R0720s or 920s (or 921s), though again--further on into GWOT, this has changed, and there are quite a few R0920s and R0921s in foreign military use. The side sling mount was originally not even for the XM4/M4 program, but actually a sling adapter used with the M203, which got standardized on the M4 and M4A1 and was an option on R0777 and R0977s. There are actually several variations of the side sling swivel as well, including a simple "band" swivel, as well as the early "reversible" sling swivel (again, originally designed for the M16/M203 combination) which had a reversible bracket to match either the profile of an M16A1 or M16A2 barrel. There was also an M16A2/M4 barrel diameter specific sling swivel with a "narrow" bracket that was constant length, and then the modern "fat" bracket, which is wider in the center (where it clamps around the barrel), and narrow at the ends where the roll pins are inserted. ~Augee |
Director of Operations
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Product Development/Marketing, Military/LE Sales, Training
Tactical Night Vision Corporation - TNVC, INC.
http://www.tnvc.com
[email protected]
(909) 796-7000 Ex. 201
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Chris at Small Arms Solutions inspired me to do a clone with a Bushmaster A2 carbine (16”) Added Colt N1 stock and four position tube, 1997 Colt M4 handguards, early 90s Colt A2 grip. Now just need to install the Colt side sling swivel. 
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XM4 Clone/Information thread (Page 1 of 3)
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