Colt SMG: First of the 9mm ARs

Published on August 8, 2025
Duration: 13:32

The Colt SMG, a 9mm variant of the AR-15 platform, was developed to compete with the HK MP5 for law enforcement. It features a closed-bolt, blowback action, distinct from the AR-15's direct impingement system. Modifications include Uzi-based magazines with AR-style release notches and a bolt hold-open feature, a plastic gas deflector, and upgraded fire control pins for durability.

Quick Summary

The Colt SMG is a 9mm submachine gun based on the AR-15 platform, featuring a closed-bolt, simple blowback action. It uses modified Uzi magazines and includes a plastic gas deflector. Its rate of fire was adjusted to 700-900 RPM for better control.

Chapters

  1. 00:00Introduction: Colt SMG vs. MP5
  2. 01:13Early Development & Closed-Bolt Design
  3. 02:31Rate of Fire & Weight Adjustments
  4. 03:23Receiver Markings & Serial Numbers
  5. 04:04Uzi Magazine Modifications
  6. 05:13Gas Deflector & Dust Cover
  7. 06:07Internal Blowback System Explained
  8. 07:38Lower Receiver & Feed Ramp
  9. 09:18Fire Control Group Upgrades
  10. 09:53Market Performance & Variants (DOE, DEA)

Frequently Asked Questions

What makes the Colt SMG different from a standard AR-15?

The Colt SMG operates on a simple blowback system, unlike the AR-15's direct impingement gas system. It uses a solid bolt carrier without a gas key and is chambered in 9mm, requiring specific lower receiver modifications and magazines.

How did Colt modify Uzi magazines for the Colt SMG?

Colt adapted 25 and 32-round Uzi magazines by adding a notch for the AR-style magazine release. They also included a tab on the follower to activate the bolt hold-open feature, which the original Uzi magazines lacked.

What was the purpose of the plastic gas deflector on the Colt SMG?

The distinctive plastic gas deflector, added in 1986, was designed to protect shooters from hot gas and debris ejected from the weapon. This required shortening the standard AR-15 dust cover to fit the modified ejection port.

What rate of fire did the Colt SMG achieve after modifications?

Initial prototypes had a very high rate of fire around 1200 RPM. Engineers increased the weight of the bolt and buffer to reduce this to a more controllable range of 700 to 900 RPM.

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