Uploaded May 2026 | Updated September 2026, 3 weeks ago
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EDIT: Sorry, my mistake here; the HK33 always used a single-pin stock.
The very first iteration of the HK 33 roller-delayed rifle was included in early US rifle testing in Vietnam. H&K worked with Harrington & Richardson as their US representative, who did final assembly on a small number of trials rifles and marked them "H&R T223". These went to Vietnam for testing and while the Army opted to stick with the M16, at least one of the test guns was kept by a member of Seal Team 2 and used in combat later (this is where the Vietnam photos of the T223 come from).
The T223 is most unusual for having an automatic bolt hold-open, a feature not seen in another 5.56mm H&K rifle until the trials G41 model. This hold open only functioned when the rifle was actually fired empty; it did not engage when the bolt was manually opened with the charging handle. While unique magazines are required for the hold open feature, regular HK33 magazines do function otherwise. The T223 includes a number of other very early features including a rib for a detachable bipod, a single-pin buttstock, cut-down G3 handguard, unique rear sight configuration, and lack of buffer in either the buttstock or bolt carrier.
Thanks to the Institute of Military Technology for allowing me to have access to these prototypes and bring them to you! Check them out at:
instmiltech.com
The best firearms reference books: headstamppublishing.com
floatplane.com/channel/ForgottenWeapons
Cool Forgotten Weapons merch! shop.forgottenweapons.com
Join the Forgotten Weapons Patreon for direct ad-free videos:
patreon.com/ForgottenWeapons
EDIT: Sorry, my mistake here; the HK33 always used a single-pin stock.
The very first iteration of the HK 33 roller-delayed rifle was included in early US rifle testing in Vietnam. H&K worked with Harrington & Richardson as their US representative, who did final assembly on a small number of trials rifles and marked them "H&R T223". These went to Vietnam for testing and while the Army opted to stick with the M16, at least one of the test guns was kept by a member of Seal Team 2 and used in combat later (this is where the Vietnam photos of the T223 come from).
The T223 is most unusual for having an automatic bolt hold-open, a feature not seen in another 5.56mm H&K rifle until the trials G41 model. This hold open only functioned when the rifle was actually fired empty; it did not engage when the bolt was manually opened with the charging handle. While unique magazines are required for the hold open feature, regular HK33 magazines do function otherwise. The T223 includes a number of other very early features including a rib for a detachable bipod, a single-pin buttstock, cut-down G3 handguard, unique rear sight configuration, and lack of buffer in either the buttstock or bolt carrier.
Thanks to the Institute of Military Technology for allowing me to have access to these prototypes and bring them to you! Check them out at:
instmiltech.com
The best firearms reference books: headstamppublishing.com
floatplane.com/channel/ForgottenWeapons
Cool Forgotten Weapons merch! shop.forgottenweapons.com
