Stripped upper receiver: no forward assist, no ejection-port cover, no parts installed. Colt M4 Upper Receiver, Raised C, Cerro Keyhole — NOS Factory Seconds, tested functional

These are New Old Stock 2017 Colt M4 stripped upper receivers 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, priced as factory seconds.

Highlights

• Stripped Upper Receiver — No forward assist, ejection-port cover, bolt carrier group or charging handle.
• 2017 New Old Stock Colt — From the closing period of Colt's traditional raised-C upper receiver production.
• Faint 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.
• Machined Off Center — Does not meet Colt specs, but tested functional.
• M4 Feed Ramps — No T-marks on the rail, no dry-film lube interior and no M4 marking above the gas tube hole.

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.

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 by grade.

Factory 2nds

The QA for the military is not met, but will work fine for the occasional 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.

Technical Specifications

NOTE:  NO RETURNS PERMITTED FOR ANY REASON.

Factory 2nds are offered at a price low enough for the cloner who wants to experiment. If it meets your needs, great. If not, it was a fun experiment.