Colt M4 Upper Receiver, Raised C, Cerro Keyhole — NOS Factory Seconds - but functional

These are New Old Stock 2017 Colt M4 upper receiver assemblies from the final period of the traditional raised-C receiver, using Cerro keyhole forgings. This particular offering is our Factory 2nds. 

This receiver did not pass final QA to technically be accepted by Colt.  The upper is not centered.  We have tested these as functional, but the left side of the upper is cut close, resulting in less side material on the left and more on the right.

For the clone builder, this is an unusual opportunity. These are genuine late-production raised-C Colt uppers from just before Colt's broad transition to CAGE-code markings, but priced according to the cosmetic quality of a marking that collectors normally pay a premium to obtain.

Highlights

• 2017 New Old Stock Colt — From the closing period of Colt's traditional raised-C upper receiver production.
• Grade C Raised C — Genuine Colt C remains present, but is very faded and considerably less distinct.
• Cerro Keyhole Forging — Correct raised keyhole forge identifier from Cerro's Virginia forging operation.
• Off Center Forging — Does not meet Colt specs, but fully functional
• M4 Configuration — M4 feed ramps and front M4 marking.
• Complete Receiver Assembly — Forward assist and ejection-port cover are installed.

[IMAGE: Close-up of actual Grade C receiver showing the faded raised C and Cerro keyhole]

The End of the Raised-C Era

For years, one of the easiest visual clues on a Colt flat-top upper was the raised C beside the forge identifier. The adjacent keyhole identifies the forging source as Cerro; the C is the Colt marking collectors look for.

This group dates to 2017, very late in the traditional C-marked period. Around 2018, Colt's 13629 CAGE-code markings became increasingly common on upper receivers and other components. As is typical with Colt, there was overlap rather than a single clean production cutoff.

What makes these receivers different is the condition of the forging die.

By this late production run, the portion of the die creating the raised C was no longer producing the tall, crisp mark associated with a fresh die. The receiver itself remained entirely serviceable, but the appearance of the C varied enough that Charlie's separates these receivers into three grades.

Factory 2nds

The QA for the military is not met, but will work fine for the occaisional shooter.  Pics show the reaming of the back of the receiver to be off-center, showing less material to the left of the charging handle, and more to the right.

Additionally, the top Picatinny rail lacks T-markings, there is no dry-film lube interior and no M4 marking about the gas tube hole.

Technical Specifications

NOTE:  NO RETURNS FOR NON-FUNCTIONAL IMPEFECTIONS