Please click here to visit the "Military Rifle Components Guide" for
additional info and photos of the various components used on this model.
HISTORY / BACKGROUND:
The Colt Model 604 was the AR-15/M-16 model developed primarily for the US Air Force. It differed from the
XM16E1 and M16A1 in that it did not have the forward assist feature. The "early" models were built with a
Partial Fence Lower and 3-Prong Flashhider, and the "late" models were built with Full Fence Lowers and
A1 Birdcage Flashhiders.

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BUTTSTOCK:
STYLE:
Later / Improved Solid Body
Type D


BUTTPLATE:
Solid Rubber



SWIVEL:
Pinned, Metal with
Plastic Covering


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BUFFER GROUP:
BUFFER:
Early - Edgewater Spring Guide
Late - Improved / Current Rifle Buffer


SPRING:
Standard Rifle Spring


TUBE:
Early - Original Tube, without Wrench Flats
Late - Improved Tube, with Wrench Flats on the End
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LOWER RECEIVER:
STYLE:
Early - "Partial Fence"

Late - "Full Fence"

MARKINGS:
Colt Logo
COLT AR-15
PROPERTY
OF U.S. GOVT.
M 16
CAL. 5.56 MM.
Serial XXXXXX


SELECTOR:
"Later"


TAKEDOWN / PIVOT PINS:
"Later" Pins


BOLT CATCH/RELEASE:
"Latter" with Raised/Grooved End
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UPPER RECEIVER:
PROOF MARKS / FORGE CODE:
Colt Proof Marks - Triangle & Square with "C"
Located in front of ejection port
No Forge Code


REAR SIGHT:



EJECTION PORT COVER:
"Later" with " Rectangular Plate"
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BOLT GROUP:
CARRIER:
Early - Possible Transitional Bolt, Mix of Parts
Late - Parkerized with Forward Assist Serrations

BOLT:
Chrome or Parkerized

FIRING PIN:
Improved Light Flat Head


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CHARGING HANDLE:
Current Improved Design







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HANDGUARD SLIP RING:
Flat





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BARREL:
DIAMETER:
0.625" at the Front Sight Base

LENGTH:
20"

TWIST RATE:
1/12

MARKINGS:


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HANDGUARDS:
Standard Triangular





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FRONT SIGHT BASE:
STYLE:
Forged


MARKINGS:
None







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FLASHHIDER:
Early - Improved 3 Prong Flashhider




Late - A1 Birdcage
1967 - Vietnam
US Navy "Brown Water" Patrol
RETRO BLACK RIFLE - RIFLE GUIDE - MODEL 604
Unknown Date - Vietnam
US Navy
Unknown Date - Vietnam
Oct 1989 - Eglin AFB, FL
Sgt. Lee of the base's security police issuing a M-16 rifle. This
is also an early Model 604 with various upgrades.
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ADDITIONAL COLT MODEL 604 INFORMATION
Oct 1981 - Osan Air Base, KOR
Senior Airman Malerva, 432nd Security Police Squadron,
during the ground base defense exercise Foal Eagle '91.
This is an "early" Model 604 with the Partial Fence Lower,
but the Flash Hider has probably been upgraded from an
Improved  3 Prong to an A1 Birdcage.
June 1984 - Camp Robinson, AR
Sergeant Peterson, from the 314th Security Police
Squadron participates in Exercise SAFE DEFENDER ONE
as a member of the aggressor force. This is a "late" Model
604, as indicated by the Full Fence Lower.
January 1984 - Little Rock Air Base, AR
Airman Donald during Exercise VOLANT SCORPION. This is
also an example of a "late" Model 604.
setstats
.223 Cal / 5.56mm
MILITARY RIFLE
GUIDE
Military Rifle
Components Guide
Colt Model 601
Colt Model 602
Colt Model 603 /
XM16E1
Other M16A1
Manufacturers
Colt Model 604 /   
USAF M16
Colt Model 603
M16A1
Colt Model 606
HBAR
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