H&R T223: In Vietnam Before the HK33

Published on May 18, 2026
Duration: 15:44

This video provides an in-depth look at the rare H&R T223, a precursor to the HK33, detailing its history, unique features, and operational mechanisms. The presenter, Ian McCollum of Forgotten Weapons, highlights its testing in Vietnam and contrasts its design with later HK models, particularly focusing on its experimental automatic bolt hold open system.

Quick Summary

The H&R T223 was the first prototype of a .223 caliber HK roller-delayed rifle, tested by the US Army in Vietnam from 1964-1966. It featured a unique automatic bolt hold open mechanism that engaged only after firing the last round, a design element not carried over to the production HK33.

Chapters

  1. 00:00Introduction to the H&R T223
  2. 00:11First Iteration of .223 HK Roller-Delayed Rifle
  3. 00:19Harrington & Richardson T223 Overview
  4. 00:24Progenitor of the HK33
  5. 00:29US Testing in Vietnam (1964-1966)
  6. 00:37Small Arms Weapons Systems Test
  7. 00:50Tested Weapons: M16E1, AKM, Stoner 63, M14, H&R .223
  8. 01:02H&R as H&K's US Arm
  9. 01:13Combat Use in Vietnam by SEAL Team 2
  10. 01:24Comparison to Standard HK33
  11. 01:31Automatic Bolt Hold Open Feature
  12. 01:45Markings: H&R, Inc., T223, Calibre 5.56
  13. 01:56Selector Markings: Safe, Semi, Auto
  14. 02:04Bolt Release Lever
  15. 02:15Bolt Hold Open Magazine Requirements
  16. 02:22T223 Magazine Design
  17. 02:45Bolt Hold Open Mechanism Demonstration
  18. 03:03Bipod Lug and Receiver Mount
  19. 03:25Modified G3 Handguard
  20. 03:57Rear Sight Calibration (100, 300, 400m)
  21. 04:00MP5-Style Buttstock
  22. 04:33Disassembly: Buttstock Pin, Recoil Spring
  23. 04:54Disassembly: Trigger Group, Bolt Carrier
  24. 04:51Bolt Hold Open System Components
  25. 05:12Cutaway Hammers
  26. 05:39Magazine Well Interaction
  27. 06:07Bolt Locking Mechanism Explained
  28. 06:34Bolt Release Function
  29. 06:48Deliberate Bolt Hold Open Design Choice
  30. 07:25Reloading and Bolt Release Procedure
  31. 07:57Post-Testing History and Combat Use
  32. 08:12Evolution to HK33
  33. 08:22HK33 Adoption and Global Use
  34. 08:51Rarity and Preservation of T223
  35. 09:03Thanks to IMT

Frequently Asked Questions

What was the H&R T223?

The H&R T223 was the first prototype of a .223 caliber roller-delayed rifle developed by Harrington & Richardson for Heckler & Koch. It was tested by the US Army in Vietnam as a potential alternative to the M16 rifle.

What was the purpose of the H&R T223's testing in Vietnam?

The H&R T223 was part of the US Army's Small Arms Weapons Systems Test from 1964 to 1966. The goal was to evaluate the viability of various weapon platforms, including the T223, for use in the Vietnam conflict alongside the M16.

What made the H&R T223 unique compared to the later HK33?

The most significant unique feature of the H&R T223 was its automatic bolt hold open mechanism, which would lock the bolt open after firing the last round. Standard HK33 production models omitted this feature.

How did the H&R T223's bolt hold open mechanism work?

The T223's bolt hold open system involved a two-part mechanism: a lever in the fire control group and a component in the magazine well that interacted with a tab on specialized magazines. It only engaged when the rifle was fired empty, not when manually cycled.

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