No, A4's do not have M4 ramps.

Tried reading the initial Info but it blanks out after 10 seconds & leaves only the Pictures,What gives?

So what are these stamp marks all about on my M-16 pre-A1?

"C" in a box = Colt
"VP" in a triangle = Verified Proof

just means it's a Colt receiver that was assembled into a rifle or carbine and proof fired

After a brief cursory perusal of this thread, I see no mention of the differences between the variations of lower receivers.  Did I miss this somewhere, or is it still coming?  I know some have large front pivot holes, some have small holes, some have more ridges machined into the sides, particularly the right side of the mag well.  This is particularly of interest to me in when looking at potential transferrable registered receivers to know exactly what I'm getting.  Thanks.

You need the other thread: AR15/M16A1 Lower Receiver: Model Guide/Clone Building Guide/FAQ, redux.

Also, please note that these references are for USGI models, and as such, there are no large pivot pin models discussed.

Ekie
      Were there two differant 603 uppers a early square forge and a round forge like the 604?

I'm not Ekie, but yes.

Gloss hand guards were factory original on our early A2's along with the large diameter w/ flat F/A. We received our A2's brand new when they were fielded en mass to the 9th I.D. Ca.1988

Smooth surface would be a more appropriate description IMHO. The gloss did not appear right away but only after some use. A good vigorous Infantry style cleaning would rapidly accelerate the process.

The only thing cooler than unpacking 65 of them to verify Sn#'s was putting the first round down range out of mine.

Units of the 9th I.D. that received A2's later received rifles with matte hand guards.

Edit to add

The top hand guard in the pic is earliest A2 like we had.
Middle could be considered a transitional model hand guard I.E. gloss with a matte finish on the heat shield under the vent holes.
Bottom is subsequent and current matte/ matte.

Agreed. Nice research.......

10,000,000 serial number range
1997-
US Property marked Colt's/FN M16A4

Anymore info regarding what years/serial range?

I've been issued Colt M16A4 serial 10026928, & FN M16A4 serial 10203321, I'd like to know the years if possible they were made? Also had M4A1 serial W356362 if anyone knows that as well?

James

WOW

AWESOME thread.

I have an example. I didn't even know this was special until someone pointed it out in a thread I posted.

This is a M16A1 rebuilt to M16A2 standards photographed at the Small Arms Firing School - Rifle at Camp Perry a few years ago. I fired this rifle in the SAFS.

The serial is much easier to read on the original photo, especially when you zoom in a little.

943370

If anyone wants proof I can e-mail the original photos at higher resolution.

As long as the components meet spec/pass inspection from the Govt's perspective the contract was fulfilled by Colt.

I don't think I ever saw an M16A2 or A4 in the Army with standard handguards that didn't have a sheen to them from CLP or sweat.

This may be a dumb question, but did anyone smarter than me think to save all the reference photos before photobucket went Tango-Uniform?

Originally Posted By Ekie:
Eventually the variation guide will cover much more, figured I could start with the flash suppressor and the butt stock screw, and add the other parts in between here and there, here is a start (not covering Navy rifles such as the M16A3, or Carbines).

Special thanks goes to WpnsMan his data base of early M16A1 and M16A2 rifles has been indispensable.

USGI SERIAL NUMBER DATA BASE (serial numbers listed in chronological rather then numerical order):

101-14,484
1959-1963
US Air Force/Project AGILE/SEAL issue Colt's AR-15 Model 601, roll marked ARMALITE.  Some sold commercially to police departments, small numbers to foreign militaries such as Malaya, India, Australia, Burma, and Singapore.

20,000-39,999
1963-1964
US Property marked AR-15 Colt's Model 02 issued to US Advisors in Vietnam, and US Air Force.  Few hundred commercial/export examples were made that lack US Property markings.

40,000-49,999
1964
US Property marked US Air Force M16 Colt's Model 604.

50,000-199,999
1964-1965
US Property marked US Air Force M16 Colt's Model 604 & US Army XM16E1 Colt's Model 603.

14,500-14,916
1965
Commercial/export CAR-15 series and US Property marked GX series for S.A.W.S. contract (note, CAR-15 refers to a family of Colt's weapons, not just short ones).

15,000-19,999
1965
Commercial/export CAR-15 series.

200,000-202,446
1965
Commercial/export CAR-15 series.

202,447-379,353
1965
US Property marked US Air Force M16 Colt's Model 604, and a few commercial export models.  There are also examples of commercial/export marked models using the 20X,XXX serial number range produced in the late 1960's.

400,000 series
1966-1973 or so
Only a few rifles/carbines made in this serial number range and known examples are spread out over several years of production.  Zero US Property marked rifles have been observed.  Highest know example is 418,XXX and dates from the early 1970's.

500,001-749,999
1966-1967
US Property marked XM16E1 Colt's and M16A1, both Colt Model 603.  There are also a small number of US Air Force M16 Colt's Model 604 found in this serial number range.  Serial numbers in this range were not run in order.  M16A1's have been observed with serial numbers as low as 604,505, and XM16E1's have serial numbers as high as 741,12X.

750,000-752,443
1966
Experimental HBAR.

752,444-899,999
1967
US Property marked M16A1.

900,000 through 909,999
1966-1970
US Property marked Govt. Carbines.

910,000-919,999
US Property marked Colt's M16A1 and US Air Force M16 Colt's Model 604.

920,000-999,999
No known examples.

1,000,000-1,999,999
1968-1969
US Property marked Colt's M16A1

2,000,000-2,24X,XXX
1968-1971
US Property marked H&R M16A1.

3,000,000-3,469,217 (approximate)
1968-1971
US Property marked Hydramatic M16A1.

9,000,0000 series
1970's & 1980's
In general these are 1970's and early 80's "A1" type 600 series commercial/export marked weapons.  There are some exceptions, for example US Property marked Govt. Carbines.

AL prefix
1970
Lebanese contract rifles, some 14,000 made.

Note on 4,000,000 series Colt's, there are quite a few commercial/export marked rifles/carbines mixed in.

4,000,001-4,060,000
1970
US Air Force M16 Colt Model 604.

4,060,001-4,221,800
1970
US Property marked M16A1.

4,221,801-4,285,400
1970
US Air Force M16 Colt Model 604.

4,285,401-4,521,000
1970
US Property marked M16A1.

4,521,001-4,521,850
1970
US Air Force M16 Colt Model 604.

4,521,851-4,638, 400
1970
US Property marked M16A1.

4,638,401-4,643,400
1971
Model 613 for Malaysia.

4,643,401-4,701,400
1971
US Property marked M16A1.

4,701,401-4,701,900
1971
Model 613 Commando

4,701,901-4,844,400
1971
US Property marked M16A1.

4,844,401-4,849,400
1972
Model 613 for Taiwan.

4,849,401-4,926,000
1972
US Property marked M16A1.

4,926,001-4,928,000
1972
Model 613 for Philippines.

4,928,000-4,936,400
1972
US Property marked M16A1.

5,000,000-5,4X,XXX (app)
1973-1982
US Property marked M16A1 Colt's Model 603 (not aware of any Air Force M16 Colt Model 604's with serial numbers this high).  Also some export/commercial models.

6,000,000-6,590,478 (approximate)
1983-1986
US Property marked M16A2 & US Property marked XM4 prototypes Colt's Model 720.

8,000,000 series
1980's
In general these are 700 series commercial/export marked models of the M16A2.

7,000,000-7,429,766  (approximate)
1988-2003
US Property marked FN M16A2.  There are also Balimoy M16A1 lowers restamped A2 in this serial number range.  These were used as replacement parts by Anniston.

W prefix
1994-current
US Property marked Colt's M4/A1 Carbine, Colt's Model 920/921.

A prefix
1990's on
900 series Commercial/export versions of the M4 Carbine.

10,000,000 serial number range
1997-
US Property marked Colt's/FN M16A4

PARTS GUIDE:

ArmaLite "duck bill" flash suppressor, this part was beefed up almost immediately after the AR-15 went into service, and was only used on the Model 01 AR-15. Apparently the tongs busted off, and they are prone to spread from gas pressure, and removal/installation.
Attached File


Beefed up three prong flash suppressor, was used from 1963 through part of 1967 on late AR-15's (Model 02), the M16, XM16E1, and some early M16A1's:
Attached File


Soon after M16A1 production and just prior to chrome being added to the M16A1 chamber the flash closed "bird cage" suppressor was introduced:
Attached File


The M16A2 went into production with a new flash suppressor that omitted the bottom slot so as to decrease the dust signature created from firing.  Also used on the M16A4):
Attached File


Early lock washer on left, as used on the AR-15, XM16E1, M16, and M16A1.  Middle is the A2 peel washers used to time the A2 flash suppressor to TDC on the M16A2 and early A4's.  Right is the current crush washer used on the A4 starting in 2000:
Attached File


Special thanks goes to Model_One , captrichardson, tgus, and Victor Mederos (US Anodizing) for thier assistance in gathering info on 601 barrels.

Colt had no rifle barrel manufacturing capability at the time that the Colt/ArmaLite Model 601 into production in December of 1959.  Model 601 barrels were made by Winchester, six groove, 1/14, and broach cut.  These barrels were originally turned down to app. .565" in front of the front sight base.

This early example is stamped with two W's, one under the FSB, the other just behind the handguard cap near TDC.  The M is stamped on the exposed part of the barrel between the legs of the FSB on the right side.  This barrel also has a witness mark at TDC, and the gas port hole is counter bored:
Attached File


Close up of the exposed M marking on the right side:
Attached File


W stamping under the guards and behind the handguard cap:
Attached File


Colt increased the diameter of the AR-15 barrel beyond ArmaLite's original specs during production of the Model 601.  Diameter was increased from app. .565" to app. .575" in front of the front sight base.  This barrel profile was carried over into 602/603/604 production.  These later 601 barrels have not been observed with the counter bored gas port.  Here are some examples of markings that CAN be found on these later production Model 601 barrels:

Barrel extensions were stamped stamped with a C at the 12 o'clock position:
Attached File


Small upside down V stamp, can be found on either the left or right side of the barrel between the legs of the front sight base:
Attached File


M&S stamping on right side between legs of the front sight base.  This is probably the most common 601 barrel marking:
Attached File


C in Square Colt proof mark on barrel breach:
Attached File


Colt Verified Proof V&P in triangle marking on left side of the barrel between the legs of the front sight base:
Attached File


M1 stamped in front of the FSB:
Attached File

photo by Model_one

W near the muzzle:
Attached File

photo by Model_One

While the standard 1/14 .224 barrel twist was quite successful in commercial firearms it did not serve the AR-15 well. M193 ammunition utilizes a boat tail projectile rather then the more common flat base. Boat tail bullets have less bearing surface to engage the rifling of the bore then flat base bullets of the same weight. The result was that the 55 grain FMJBT bullets were on the edge of stability when fired from the AR-15.  Accuracy testing conducted by the US Army, US Air Force, and the NRA showed unacceptable accuracy with the 1/14 twist.  Because of these factors a twist change to 1/12 was approved on July 26th, 1963.

Here are some examples of markings found on a 1/12 twist Model 601 barrel:

Attached File

photo by tgus

Attached File

photo by tgus

Model 601 production ended in 1963 and was replaced by the Model 602. The Model 601 was chambered differently then later Colt rifles. These barrels were chambered per ArmaLite specs with significantly shorter leade/throat then was used from the Colt Model 602 through current. With the exception of examples with heavily worn throats 601 barrels gauge a 0 with my commercial T/E gauge. 602 and later barrels gauge a 1.25 when new with this same gauge.

Model 602 barrel were manufactured in house were proof tested and like some 601 barrels were stamped with Colt's proof stamp a V & P in triangle (Verified Proof) on the right side, the barrel extension was also marked with a C (C stamp was used through 1965):
Attached File


A "12" marking was added just over and inch from the muzzle to differentiate it from the earlier barrels.  Marking was used from 1963 till the Fall of 1967:
Attached File


In 1964 Colt's began marking a M next to the VP marking meaning the barrel had been magnetic particle testing after proof firing to find potential flaws in the barrel:
Attached File


By 1966 barrels were proof marked in the same spot as before, but the proof symbol was changed to a P, so they now simply read MP, with the M & P run together.  This MP marking was moved by 1969.
Attached File


Starting in October 1967 and prior to serial number 800,000 Colt's added chrome to the chamber.  Chrome chamber barrels are identified by a C about an inch back from the muzzle rather then the earlier 12:  
Attached File


Rather then being marked on the right side some H&R barrels were marked with an unside down MP on the left side.  These barrels had chrome chamber, so they also had the C mark near the muzzle:
Attached File


Chrome chamber barrels were also plated in the barrel extension:
Attached File


By 1969 and before serial number 1,750,XXX Colt's chrome chamber barrels were marked C MP C, and the proof markings and C were moved to the same spot.  This marking was used as late as 1970 or 1971 and serial number 4,552,XXX.  The C means Colt's, the M means Magnetic particle inspected, the P for Proof fired, and the C near the muzzle for Chrome chamber.  (late C MP C pic provided by yfs200):
Attached File


Some 1969 CMPC barrels had chrome all the way out onto the locking lugs and part of the feed ramps.  1969 CMPC barrel on right, chrome chamber and bore barrel on the left:
Attached File

Effective in December 1971 at about serial number 4,700,000 along with the chamber the bores were chromed, early ones were marked C MP B.  The C means Colt's, the M means Magnetic particle inspected, the P for Proof fired, and the B for chrome Bore.  The barrel extention on these not chromed:
Attached File


Starting in 1974 and after serial number 4,900,000 chrome bores were marked C MP CHROME BORE.  This marking was used all the way until the end of M16A1 production:
Attached File


M16A2/A4 barrels are marked C MP 5.56 NATO 1/7.  The C MP marking means the same as before.  The NATO 1/7 specifies the rifle is designed for NATO standard ammo rather then M193 as used with earlier rifles.
Attached File


Sometime in the mid 1980's a star is stamped on the the barrel near the chamber area.  This is probably a precursor to the later O stamp indicating a chrome chamber and bore:
Attached File


Some mid 1980's barrels are stamped 885 under the handguards, meaning unkown:  
Attached File


Starting as early as 1989 a single or two digit code by the front sight base is used, this one marked 28.  Not sure of the meaning, maybe a lot code?
Attached File


As early as 1989 an O is stamped by the chamber (some look like C's) indicating a chromed chamber/bore:
Attached File


Starting in 95 a date code is stamped by the front sight base (earlist know is 02/95).  First two digits is the month, second two digit number is the year, this one 03/02 (gas tube is yellow from full auto 30 round mag dumps, so yes I do shoot em):
Attached File


Beginning in the late 90's a paint mark is added in front and under the barrel nut, not sure of it's meaning:
Attached File


ArmaLite front sight base was cast.  This part was used on the AR-15, and early M16, and XM16E1 rifles:
Attached File


The cast front sight base was replaced by a forged part for obvious reasons. The first version of the forged front sight base was machined smooth to remove forging flash and used on M16 and XM16E1 rifles, and on the M16A1 for a time.  Production started as early as 1964, and was used as late as 1969 and serial number 1,750,XXX.  A bottom drain hole for the front sight post assy was added in 1967:
Attached File


Later forged front sight base used on later M16/A1 rifles.  These usually have a raised C and a Bell.  The C and a Bell was in use by 1970, and serial number 4,500,000:
Attached File


Early M16A2 front sight base same as a late A1 FSB with a C and a bell but with a .750" barrel journal.  This FSB was used as late as serial number 6,210,000:
Attached File


Mid to late M16A2 barrel has a raised Bfi marking inside a diamond, can be found on left or right side:
Attached File

(photo by xcibes)

Colt M16A2 conversion kits/replacement barrels, M16A4 FSB's and late replacement M16A1 barrels have a jibberish forge code:
Attached File


The M16A4 front sight base is similar to the late M16A2's, except that the platform the sight post screws into is higher, these are marked with an F on the left side:
Attached File


Front swivels were originally bare steel, and secured with a roll pin:
Attached File


Starting in 1964 the swivel is rubber coated, and was riveted on by about 1970 and serial number 4,500,000:
Attached File


Early front sight post was round.  One 360 degree rotation equaled 5 MOA, one click equals 1 MOA:
Attached File


Current square sight post used on M16A2 and M16A4.  One 360 degree rotation equaled 5 MOA, one click equals 1.25 MOA:
Attached File


ArmaLite gas tubes were carbon steel.  These were used on the AR-15, and on the M16/XM16E1 for a short time before switching to stainless steel:
Attached File


New bend was in use by 1969 and serial number 1,750,XXX:
Attached File


Since Colt did not make their own handguards and used multiple vendors, and handguards are frequently replaced on USGI rifles this is a real tough subject to pin down. I don't have dates on all of these, but do see several distinct variations. This does not come close to covering all the details, but will give you an idea.

Type A and B.  Top is first production brown fiberglass, bottom is brown fiberglass painted green paint, or "B".  Notice that the heatshield is different:
Attached File

Attached File

Type B.  Far as I know all 8,500 of the Model 601's that AF General LeMay purchased were all painted green.  Same story with the 1,000 601's purchased for Project AGILE.  Note the highlighted area and red markings:
Attached File


Close up of highlighted area:
Attached File


Type C, now black impregnated.  Starting in 1963 with the Colt Model 602 the furniture is black.  These handguards are the same shape as the Type B, note that the highlighted area is the same as the earlier guard:
Attached File


Both Type B and C handguards are frequently marked with red markings on the heat shields (Type C shown):
Attached File


Type D is the same as Type C but now has a new shape in the highlighted area:
Attached File


Close up of highlighted area:
Attached File


Type E, same as D but now with "drain holes" added to the heat shields:
Attached File


Type F handguard heat Shields are marked L and R for.  There is numerous variations of these types of handguards and I am far from figuring them out:
Attached File


A2 handguards were used on the A2 and the A4.  They range from matte to gloss.  At this point I am thinking that the gloss ones are replacement parts rather then factory original.
Attached File


This A2 handguard is marked DO NOT REMOVE, mold marks are present at every circle (highlighted).  Note placement of bend in shield:
Attached File


This handguard is not marked DO NOT REMOVE, mold marks are present at every other circle (highlighted).  Note placement of bend in shield:
Attached File


This A2 handguard is marked DO NOT REMOVE, mold marks are present at every circle (highlighted).  Note placement of bend in shield is at a different spot then the other two pictured above:
Attached File


Starting in 1999 the heatshield tabs were glued to the handguards:
NOT PICTURED

ArmaLite handguard retaining ring used on the AR-15, M16, XM16E1, and the M16A1:
Attached File


Handgaurd retaining ring used on the M16A2, and the M16A4:
Attached File


ArmaLite port door. This part was used on the AR-15, and early M16 and XM16E1 rifles, and was dropped in 1964:
Attached File


Later M16 and XM16E1 rifles used a new port door starting in 1964. This port door was also used on the M16A1:
Attached File


The M16A2 came out with a new port door that is still in use today:
Attached File


Bolt/carrier groups.  Top is the early AR-15 and M16 bolt group, no forward assist cuts.  Later transitional M16 bolt group is not pictured (mix of chrome and parked parts).  Second down is the early XM16E1 bolt group, has added forward assist cuts.  Next is the late XM16E1 and M16 and early M16A1 bolt group, now parked (transitional bolt groups are a mix of chrome and parked parts).  Third from bottom is the later C marked M16/A1 bolt group.  Second from bottom is the M16A2 bolt group.  Bottom is the M16A4 bolt group, it is parked a lighter color:
Attached File

Attached File


Top three pictured carrier keys are staked with two strikes, some were done round, and other square (pictured).  Bottom three carrier keys have a more secure stacking method that has been in use by 1967:
Attached File


Bottom three carriers are marked with a C makers code, this went into effect in about 1967, and can be found on M16A1 carriers with serial numbers as low as 807,XXX.
Attached File


Starting in the about 1995 a step was added to the carrier right behind the firing pin retaining pin.

Right view:
Attached File


Left view:
Attached File


ArmaLite firing pin on top, current on bottom.  Old part caused slam fires, and the new Colt's design was put into production in 1963:
Attached File


Early machined ArmaLite firing pin retainer:
Attached File


Current firing pin retainer:
Attached File


The forward assist was first used on the XM16E1 in 1964. This part was also used on the M16A1:
Attached File


A new forward assist was used on the M16A2, and was used as late as serial number 6,280,000:
Attached File


Newer A2 forward assist went into production in the late 1980's.  This part is still being made for use on the M16A4:
Attached File


ArmaLite charging handle was cool looking, but was hard to grab onto, it was replaced at about the same time that the M16/XM16E1 went into production in 1964
Attached File


ArmaLite bolt stop used on the AR-15, and early examples of the M16 and XM16E1:


Transitional bolt stop.  These were used sporadically and can be found on serial numbers as low as 40,XXX in 1964 and as high as 138,XXX in 1965:(photo by tgus)Current bolt stop in use since 1964: Attached File
ArmaLite edgewater spring guide. This part was used in the AR-15, M16, and the XM16E1 until Dec 1966: Attached File
The spring guide was replaced with a buffer at about the time that the XM16E1 was adopted Standard A. It is still in use. There are some variation in buffers, hope to have pics up later: Attached File
Type A buttstocks were brown fiberglass and after the first 100 rifles or so they were painted green:Type B was in use sometime before serial number 8,000, the shape of the buttstock was changed.  Note the angle at the bottom where it leaves the back of the lower receiver.  The rubber coated swivel on this example is a replacement part:Type C appears to be the same thing as B but now black.  This buttstock was used first on the Model 602 in 1963:Type D is also black, but has a slightly different shape and was first used on the 604/603 in 1964:Type E has a trap door for a cleaning kit, was introduced in 1971:The M16A2 buttstock is about 5/8" of an inch longer then the earlier models.  Because of the increased length it used a longer buttstock screw and a spacer.  The swivel is mounted closer to the buttplate.  This buttstock is currently used on the M16A4:Type A, B, and C buttstocks are smaller in diameter then the receiver ring at the back of the lower:Not only was the Type D a different shape then earlier buttstocks, it is also thicker and fits flush with the receiver extension ring.  E and A2 buttstocks also fit flush:Far right buttstock is a Type D and has a hole drilled in the front face (that white spot).  Most Type D buttstocks have this feature, while the other buttstocks lack it (also note the different lower contour on the D buttstock compared to the C next to it):Type A through D have a glued on buttplate (early examples had a ArmaLite logo):Type E had a trap door for buttstock (there is quite a bit of variation in these buttplates and trap doors that will be covered later):A2 buttplate is checkered along with the trap door:Earlist version of the rear swivel rotates 360 degrees.  The roll pin that retains the assy is also located in a different spot, so this swivel assy should not be interchangeable with later buttstocks.  It is unclear wether or not this part was dropped from production prior to the first US Air Force contract:Type A, B, and C buttstocks lacked a rubber coating on the swivel:Type A:Type C:Type D buttstock had a rubber coated swivel starting very early in production in 1964:Type E had a fixed rear swivel that again lacked a rubber coating:A2 rear swivel, similar to the Type E but placed farther back, and not interchangeable:[img]http://img.photobucket.com/albums/0603/Ekie12091941/variation%20guide/swivelrearA2.jpg" />From left; early buttstock screw with no drain holefirst version of buttstock screw with drain holelater drain hole screw with compound on threadslonger A2 screwspacer used with the A2 buttstock and longer screw[img]http://img.photobucket.com/albums/0603/Ekie12091941/variation%20guide/buttstockscrews-1.jpg" />

I'm uploading the rest of the pics in batches of 5 (my limit) to support the re-post.

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Attached File


Attached File


Attached File


Attached File


Attached File

Insight into “jibberish” gas block forge code. RI circle gas block forge Colt AR-15 M16A2 History of Providence Tool Company (doesn’t seem to upload video on here, but I did link the video. You can go to the Cav Trooper 19D channel too of course.)

https://youtu.be/VO0gfJxi_9Q

https://www.YouTube.com/c/CavTrooper19D

Found this photo with Colt Model 605 style upper in USAF inventory dated 2003.

US Air Force (USAF) STAFF Sergeant (SSGT) Pete Glassberg, 51st Communications Squadron (CS), guards the Communications building with a 5.56 mm M16A1 rifle during the contingency Exercise Beverly Midnight 03-4 at Osan Air Base (AB), Republic of Korea (ROK) 01/12/2003

I'm glad I found this thread since i just picked up a lot of M16A1 parts.