Small Arms Review
  • Home
  • Articles
    • Guns & Parts
    • Suppressors
    • Optics & Thermals
    • Ammunition
    • Gear
    • News & Opinion
    • Columns
    • Museums & Factory Tours
    • ID Guides
    • Interviews
    • Event Coverage
    • Articles by Issue
      • Volume 1
        • V1N1 (Oct 1997)
        • V1N2 (Nov 1997)
        • V1N3 (Dec 1997)
        • V1N4 (Jan 1998)
        • V1N5 (Feb 1998)
        • V1N6 (Mar 1998)
        • V1N7 (Apr 1998)
        • V1N8 (May 1998)
        • V1N9 (Jun 1998)
        • V1N10 (Jul 1998)
        • V1N11 (Aug 1998)
        • V1N12 (Sep 1998)
      • Volume 2
        • V2N1 (Oct 1998)
        • V2N2 (Nov 1998)
        • V2N3 (Dec 1998)
        • V2N4 (Jan 1999)
        • V2N5 (Feb 1999)
        • V2N6 (Mar 1999)
        • V2N7 (Apr 1999)
        • V2N8 (May 1999)
        • V2N9 (Jun 1999)
        • V2N10 (Jul 1999)
        • V2N11 (Aug 1999)
        • V2N12 (Sep 1999)
      • Volume 3
        • V3N1 (Oct 1999)
        • V3N2 (Nov 1999)
        • V3N3 (Dec 1999)
        • V3N4 (Jan 2000)
        • V3N5 (Feb 2000)
        • V3N6 (Mar 2000)
        • V3N7 (Apr 2000)
        • V3N8 (May 2000)
        • V3N9 (Jun 2000)
        • V3N10 (Jul 2000)
        • V3N11 (Aug 2000)
        • V3N12 (Sep 2000)
      • Volume 4
        • V4N1 (Oct 2000)
        • V4N2 (Nov 2000)
        • V4N3 (Dec 2000)
        • V4N4 (Jan 2001)
        • V4N5 (Feb 2001)
        • V4N6 (Mar 2001)
        • V4N7 (Apr 2001)
        • V4N8 (May 2001)
        • V4N9 (Jun 2001)
        • V4N10 (Jul 2001)
        • V4N11 (Aug 2001)
        • V4N12 (Sep 2001)
      • Volume 5
        • V5N1 (Oct 2001)
        • V5N2 (Nov 2001)
        • V5N3 (Dec 2001)
        • V5N4 (Jan 2002)
        • V5N5 (Feb 2002)
        • V5N6 (Mar 2002)
        • V5N7 (Apr 2002)
        • V5N8 (May 2002)
        • V5N9 (Jun 2002)
        • V5N10 (Jul 2002)
        • V5N11 (Aug 2002)
        • V5N12 (Sep 2002)
      • Volume 6
        • V6N1 (Oct 2002)
        • V6N2 (Nov 2002)
        • V6N3 (Dec 2002)
        • V6N4 (Jan 2003)
        • V6N5 (Feb 2003)
        • V6N6 (Mar 2003)
        • V6N7 (Apr 2003)
        • V6N8 (May 2003)
        • V6N9 (Jun 2003)
        • V6N10 (Jul 2003)
        • V6N11 (Aug 2003)
        • V6N12 (Sep 2003)
      • Volume 7
        • V7N1 (Oct 2003)
        • V7N2 (Nov 2003)
        • V7N3 (Dec 2003)
        • V7N4 (Jan 2004)
        • V7N5 (Feb 2004)
        • V7N6 (Mar 2004)
        • V7N7 (Apr 2004)
        • V7N8 (May 2004)
        • V7N9 (Jun 2004)
        • V7N10 (Jul 2004)
        • V7N11 (Aug 2004)
        • V7N12 (Sep 2004)
      • Volume 8
        • V8N1 (Oct 2004)
        • V8N2 (Nov 2004)
        • V8N3 (Dec 2004)
        • V8N4 (Jan 2005)
        • V8N5 (Feb 2005)
        • V8N6 (Mar 2005)
        • V8N7 (Apr 2005)
        • V8N8 (May 2005)
        • V8N9 (Jun 2005)
        • V8N10 (Jul 2005)
        • V8N11 (Aug 2005)
        • V8N12 (Sep 2005)
      • Volume 9
        • V9N1 (Oct 2005)
        • V9N2 (Nov 2005)
        • V9N3 (Dec 2005)
        • V9N4 (Jan 2006)
        • V9N5 (Feb 2006)
        • V9N6 (Mar 2006)
        • V9N7 (Apr 2006)
        • V9N8 (May 2006)
        • V9N9 (Jun 2006)
        • V9N10 (Jul 2006)
        • V9N11 (Aug 2006)
        • V9N12 (Sep 2006)
      • Volume 10
        • V10N1 (Oct 2006)
        • V10N2 (Nov 2006)
        • V10N3 (Dec 2006)
        • V10N4 (Jan 2007)
        • V10N5 (Feb 2007)
        • V10N6 (Mar 2007)
        • V10N7 (Apr 2007)
        • V10N8 (May 2007)
        • V10N9 (Jun 2007)
        • V10N10 (Jul 2007)
        • V10N11 (Aug 2007)
        • V10N12 (Sep 2007)
      • Volume 11
        • V11N1 (Oct 2007)
        • V11N2 (Nov 2007)
        • V11N3 (Dec 2007)
        • V11N4 (Jan 2008)
        • V11N5 (Feb 2008)
        • V11N6 (Mar 2008)
        • V11N7 (Apr 2008)
        • V11N8 (May 2008)
        • V11N9 (Jun 2008)
        • V11N10 (Jul 2008)
        • V11N11 (Aug 2008)
        • V11N12 (Sep 2008)
      • Volume 12
        • V12N1 (Oct 2008)
        • V12N2 (Nov 2008)
        • V12N3 (Dec 2008)
        • V12N4 (Jan 2009)
        • V12N5 (Feb 2009)
        • V12N6 (Mar 2009)
        • V12N7 (Apr 2009)
        • V12N8 (May 2009)
        • V12N9 (Jun 2009)
        • V12N10 (Jul 2009)
        • V12N11 (Aug 2009)
        • V12N12 (Sep 2009)
      • Volume 13
        • V13N1 (Oct 2009)
        • V13N2 (Nov 2009)
        • V13N3 (Dec 2009)
        • V13N4 (Jan 2010)
        • V13N5 (Feb 2010)
        • V13N6 (Mar 2010)
        • V13N7 (Apr 2010)
        • V13N8 (May 2010)
        • V13N9 (Jun 2010)
        • V13N10 (Jul 2010)
        • V13N11 (Aug 2010)
        • V13N12 (Sep 2010)
      • Volume 14
        • V14N1 (Oct 2010)
        • V14N2 (Nov 2010)
        • V14N3 (Dec 2010)
          • Ammunition
        • V14N4 (Jan 2011)
        • V14N5 (Feb 2011)
        • V14N6 (Mar 2011)
        • V14N7 (Apr 2011)
        • V14N8 (May 2011)
        • V14N9 (Jun 2011)
        • V14N10 (Jul 2011)
        • V14N11 (Aug 2011)
        • V14N12 (Sep 2011)
      • Volume 15
        • V15N1 (Oct 2011)
        • V15N2 (Nov 2011)
        • V15N4 (Jan 2012)
        • V15N5 (Feb 2012)
      • Volume 16
        • V16N1 (1st Quarter 2012)
        • V16N2 (2nd Quarter 2012)
        • V16N3 (3rd Quarter 2012)
        • V16N4 (4th Quarter 2012)
      • Volume 17
        • V17N1 (1st Quarter 2013)
        • V17N2 (2nd Quarter 2013)
        • V17N3 (3rd Quarter 2013)
        • V17N4 (4th Quarter 2013)
      • Volume 18
        • V18N1 (Jan Feb 2014)
        • V18N2 (Mar Apr 2014)
        • V18N3 (May Jun 2014)
        • V18N4 (Jul Aug 2014)
        • V18N5 (Sep Oct 2014)
        • V18N6 (Nov Dec 2014)
      • Volume 19
        • V19N1 (Jan 2015)
        • V19N2 (Feb Mar 2015)
        • V19N3 (Apr 2015)
        • V19N4 (May 2015)
        • V19N5 (Jun 2015)
        • V19N6 (Jul 2015)
        • V19N7 (Aug Sep 2015)
        • V19N8 (Oct 2015)
        • V19N9 (Nov 2015)
        • V19N10 (Dec 2015)
      • Volume 20
        • V20N1 (Jan 2016)
        • V20N2 (Feb Mar 2016)
        • V20N3 (Apr 2016)
        • V20N4 (May 2016)
        • V20N5 (Jun 2016)
        • V20N6 (Jul 2016)
        • V20N7 (Aug Sep 2016)
        • V20N8 (Oct 2016)
        • V20N9 (Nov 2016)
        • V20N10 (Dec 2016)
      • Volume 21
        • V21N1 (Jan 2017)
        • V21N2 (Feb Mar 2017)
        • V21N3 (Apr 2017)
        • V21N4 (May 2017)
        • V21N5 (Jun 2017)
        • V21N6 (Jul 2017)
        • V21N7 (Aug Sep 2017)
        • V21N8 (Oct 2017)
        • V21N9 (Nov 2017)
        • V21N10 (Dec 2017)
      • Volume 22
        • V22N1 (Jan 2018)
        • V22N2 (Feb 2018)
        • V22N3 (March 2018)
        • V22N4 (Apr 2018)
        • V22N5 (May 2018)
        • V22N6 (Jun Jul 2018)
        • V22N7 (Aug Sep 2018)
        • V22N8 (Oct 2018)
        • V22N9 (Nov 2018)
        • V22N10 (Dec 2018)
      • Volume 23
        • V23N1 (Jan 2019)
        • V23N2 (Feb 2019)
        • V23N3 (Mar 2019)
        • V23N4 (Apr 2019)
        • V23N5 (May 2019)
        • V23N6 (Jun Jul 2019)
        • V23N7 (Aug Sep 2019)
        • V23N8 (Oct 2019)
        • V23N9 (Nov 2019)
        • V23N10 (Dec 2019)
      • Volume 24
        • V24N1 (Jan 2020)
        • V24N2 (Feb 2020)
        • V24N3 (Mar 2020)
        • V24N4 (Apr 2020)
        • V24N5 (May 2020)
        • V24N6 (Jun Jul 2020)
        • V24N7 (Aug Sep 2020)
        • V24N8 (Oct 2020)
        • V24N9 (Nov 2020)
        • V24N10 (Dec 2020)
  • The Archive
    • Search The Archive
  • Store
    • Books
    • Back Issues
    • Merchandise
  • Podcast
  • Newsletter
  • Events
  • FrankenGun Challenge
  • About
    • About Small Arms Review
    • About Chipotle Publishing
    • Contact Us
    • Other Publications
      • Small Arms Defense Journal
  • Home
  • Articles
    • Guns & Parts
    • Suppressors
    • Optics & Thermals
    • Ammunition
    • Gear
    • News & Opinion
    • Columns
    • Museums & Factory Tours
    • ID Guides
    • Interviews
    • Event Coverage
    • Articles by Issue
      • Volume 1
        • V1N1 (Oct 1997)
        • V1N2 (Nov 1997)
        • V1N3 (Dec 1997)
        • V1N4 (Jan 1998)
        • V1N5 (Feb 1998)
        • V1N6 (Mar 1998)
        • V1N7 (Apr 1998)
        • V1N8 (May 1998)
        • V1N9 (Jun 1998)
        • V1N10 (Jul 1998)
        • V1N11 (Aug 1998)
        • V1N12 (Sep 1998)
      • Volume 2
        • V2N1 (Oct 1998)
        • V2N2 (Nov 1998)
        • V2N3 (Dec 1998)
        • V2N4 (Jan 1999)
        • V2N5 (Feb 1999)
        • V2N6 (Mar 1999)
        • V2N7 (Apr 1999)
        • V2N8 (May 1999)
        • V2N9 (Jun 1999)
        • V2N10 (Jul 1999)
        • V2N11 (Aug 1999)
        • V2N12 (Sep 1999)
      • Volume 3
        • V3N1 (Oct 1999)
        • V3N2 (Nov 1999)
        • V3N3 (Dec 1999)
        • V3N4 (Jan 2000)
        • V3N5 (Feb 2000)
        • V3N6 (Mar 2000)
        • V3N7 (Apr 2000)
        • V3N8 (May 2000)
        • V3N9 (Jun 2000)
        • V3N10 (Jul 2000)
        • V3N11 (Aug 2000)
        • V3N12 (Sep 2000)
      • Volume 4
        • V4N1 (Oct 2000)
        • V4N2 (Nov 2000)
        • V4N3 (Dec 2000)
        • V4N4 (Jan 2001)
        • V4N5 (Feb 2001)
        • V4N6 (Mar 2001)
        • V4N7 (Apr 2001)
        • V4N8 (May 2001)
        • V4N9 (Jun 2001)
        • V4N10 (Jul 2001)
        • V4N11 (Aug 2001)
        • V4N12 (Sep 2001)
      • Volume 5
        • V5N1 (Oct 2001)
        • V5N2 (Nov 2001)
        • V5N3 (Dec 2001)
        • V5N4 (Jan 2002)
        • V5N5 (Feb 2002)
        • V5N6 (Mar 2002)
        • V5N7 (Apr 2002)
        • V5N8 (May 2002)
        • V5N9 (Jun 2002)
        • V5N10 (Jul 2002)
        • V5N11 (Aug 2002)
        • V5N12 (Sep 2002)
      • Volume 6
        • V6N1 (Oct 2002)
        • V6N2 (Nov 2002)
        • V6N3 (Dec 2002)
        • V6N4 (Jan 2003)
        • V6N5 (Feb 2003)
        • V6N6 (Mar 2003)
        • V6N7 (Apr 2003)
        • V6N8 (May 2003)
        • V6N9 (Jun 2003)
        • V6N10 (Jul 2003)
        • V6N11 (Aug 2003)
        • V6N12 (Sep 2003)
      • Volume 7
        • V7N1 (Oct 2003)
        • V7N2 (Nov 2003)
        • V7N3 (Dec 2003)
        • V7N4 (Jan 2004)
        • V7N5 (Feb 2004)
        • V7N6 (Mar 2004)
        • V7N7 (Apr 2004)
        • V7N8 (May 2004)
        • V7N9 (Jun 2004)
        • V7N10 (Jul 2004)
        • V7N11 (Aug 2004)
        • V7N12 (Sep 2004)
      • Volume 8
        • V8N1 (Oct 2004)
        • V8N2 (Nov 2004)
        • V8N3 (Dec 2004)
        • V8N4 (Jan 2005)
        • V8N5 (Feb 2005)
        • V8N6 (Mar 2005)
        • V8N7 (Apr 2005)
        • V8N8 (May 2005)
        • V8N9 (Jun 2005)
        • V8N10 (Jul 2005)
        • V8N11 (Aug 2005)
        • V8N12 (Sep 2005)
      • Volume 9
        • V9N1 (Oct 2005)
        • V9N2 (Nov 2005)
        • V9N3 (Dec 2005)
        • V9N4 (Jan 2006)
        • V9N5 (Feb 2006)
        • V9N6 (Mar 2006)
        • V9N7 (Apr 2006)
        • V9N8 (May 2006)
        • V9N9 (Jun 2006)
        • V9N10 (Jul 2006)
        • V9N11 (Aug 2006)
        • V9N12 (Sep 2006)
      • Volume 10
        • V10N1 (Oct 2006)
        • V10N2 (Nov 2006)
        • V10N3 (Dec 2006)
        • V10N4 (Jan 2007)
        • V10N5 (Feb 2007)
        • V10N6 (Mar 2007)
        • V10N7 (Apr 2007)
        • V10N8 (May 2007)
        • V10N9 (Jun 2007)
        • V10N10 (Jul 2007)
        • V10N11 (Aug 2007)
        • V10N12 (Sep 2007)
      • Volume 11
        • V11N1 (Oct 2007)
        • V11N2 (Nov 2007)
        • V11N3 (Dec 2007)
        • V11N4 (Jan 2008)
        • V11N5 (Feb 2008)
        • V11N6 (Mar 2008)
        • V11N7 (Apr 2008)
        • V11N8 (May 2008)
        • V11N9 (Jun 2008)
        • V11N10 (Jul 2008)
        • V11N11 (Aug 2008)
        • V11N12 (Sep 2008)
      • Volume 12
        • V12N1 (Oct 2008)
        • V12N2 (Nov 2008)
        • V12N3 (Dec 2008)
        • V12N4 (Jan 2009)
        • V12N5 (Feb 2009)
        • V12N6 (Mar 2009)
        • V12N7 (Apr 2009)
        • V12N8 (May 2009)
        • V12N9 (Jun 2009)
        • V12N10 (Jul 2009)
        • V12N11 (Aug 2009)
        • V12N12 (Sep 2009)
      • Volume 13
        • V13N1 (Oct 2009)
        • V13N2 (Nov 2009)
        • V13N3 (Dec 2009)
        • V13N4 (Jan 2010)
        • V13N5 (Feb 2010)
        • V13N6 (Mar 2010)
        • V13N7 (Apr 2010)
        • V13N8 (May 2010)
        • V13N9 (Jun 2010)
        • V13N10 (Jul 2010)
        • V13N11 (Aug 2010)
        • V13N12 (Sep 2010)
      • Volume 14
        • V14N1 (Oct 2010)
        • V14N2 (Nov 2010)
        • V14N3 (Dec 2010)
          • Ammunition
        • V14N4 (Jan 2011)
        • V14N5 (Feb 2011)
        • V14N6 (Mar 2011)
        • V14N7 (Apr 2011)
        • V14N8 (May 2011)
        • V14N9 (Jun 2011)
        • V14N10 (Jul 2011)
        • V14N11 (Aug 2011)
        • V14N12 (Sep 2011)
      • Volume 15
        • V15N1 (Oct 2011)
        • V15N2 (Nov 2011)
        • V15N4 (Jan 2012)
        • V15N5 (Feb 2012)
      • Volume 16
        • V16N1 (1st Quarter 2012)
        • V16N2 (2nd Quarter 2012)
        • V16N3 (3rd Quarter 2012)
        • V16N4 (4th Quarter 2012)
      • Volume 17
        • V17N1 (1st Quarter 2013)
        • V17N2 (2nd Quarter 2013)
        • V17N3 (3rd Quarter 2013)
        • V17N4 (4th Quarter 2013)
      • Volume 18
        • V18N1 (Jan Feb 2014)
        • V18N2 (Mar Apr 2014)
        • V18N3 (May Jun 2014)
        • V18N4 (Jul Aug 2014)
        • V18N5 (Sep Oct 2014)
        • V18N6 (Nov Dec 2014)
      • Volume 19
        • V19N1 (Jan 2015)
        • V19N2 (Feb Mar 2015)
        • V19N3 (Apr 2015)
        • V19N4 (May 2015)
        • V19N5 (Jun 2015)
        • V19N6 (Jul 2015)
        • V19N7 (Aug Sep 2015)
        • V19N8 (Oct 2015)
        • V19N9 (Nov 2015)
        • V19N10 (Dec 2015)
      • Volume 20
        • V20N1 (Jan 2016)
        • V20N2 (Feb Mar 2016)
        • V20N3 (Apr 2016)
        • V20N4 (May 2016)
        • V20N5 (Jun 2016)
        • V20N6 (Jul 2016)
        • V20N7 (Aug Sep 2016)
        • V20N8 (Oct 2016)
        • V20N9 (Nov 2016)
        • V20N10 (Dec 2016)
      • Volume 21
        • V21N1 (Jan 2017)
        • V21N2 (Feb Mar 2017)
        • V21N3 (Apr 2017)
        • V21N4 (May 2017)
        • V21N5 (Jun 2017)
        • V21N6 (Jul 2017)
        • V21N7 (Aug Sep 2017)
        • V21N8 (Oct 2017)
        • V21N9 (Nov 2017)
        • V21N10 (Dec 2017)
      • Volume 22
        • V22N1 (Jan 2018)
        • V22N2 (Feb 2018)
        • V22N3 (March 2018)
        • V22N4 (Apr 2018)
        • V22N5 (May 2018)
        • V22N6 (Jun Jul 2018)
        • V22N7 (Aug Sep 2018)
        • V22N8 (Oct 2018)
        • V22N9 (Nov 2018)
        • V22N10 (Dec 2018)
      • Volume 23
        • V23N1 (Jan 2019)
        • V23N2 (Feb 2019)
        • V23N3 (Mar 2019)
        • V23N4 (Apr 2019)
        • V23N5 (May 2019)
        • V23N6 (Jun Jul 2019)
        • V23N7 (Aug Sep 2019)
        • V23N8 (Oct 2019)
        • V23N9 (Nov 2019)
        • V23N10 (Dec 2019)
      • Volume 24
        • V24N1 (Jan 2020)
        • V24N2 (Feb 2020)
        • V24N3 (Mar 2020)
        • V24N4 (Apr 2020)
        • V24N5 (May 2020)
        • V24N6 (Jun Jul 2020)
        • V24N7 (Aug Sep 2020)
        • V24N8 (Oct 2020)
        • V24N9 (Nov 2020)
        • V24N10 (Dec 2020)
  • The Archive
    • Search The Archive
  • Store
    • Books
    • Back Issues
    • Merchandise
  • Podcast
  • Newsletter
  • Events
  • FrankenGun Challenge
  • About
    • About Small Arms Review
    • About Chipotle Publishing
    • Contact Us
    • Other Publications
      • Small Arms Defense Journal
No Result
View All Result
Small Arms Review
No Result
View All Result
Home Firearm History

Forgotten M16A1 Rifle Manufacturers: GM/Hydra-Matic and Harrington & Richardson – Part I

SAR Staff by SAR Staff
December 15, 2022
in Firearm History, Articles, Articles by Issue, Guns & Parts, Search by Issue, V25N8, Volume 25
Forgotten M16A1 Rifle Manufacturers: GM/Hydra-Matic and Harrington & Richardson – Part I

An M16A1 rifle manufactured by the Hydra-Matic Division of General Motors during the Vietnam War.

Share on FacebookShare on Twitter

By Frank Iannamico and Chris Cox

General Motor’s Hydra-Matic Division

The United States’ direct military involvement in Vietnam ended in 1973. During most of the war, the standard “A” infantry weapon of U.S. troops was the 5.56mm M16 rifle.

Colt’s Patent Fire Arms Company was the manufacturer of the M16 and held the exclusive rights to the design. As the Vietnam War was escalating, more rifles were needed and the U.S. government wanted to establish a second source for the weapons. However, Colt resisted the idea of relinquishing the manufacturing rights and the M16 Technical Data Package to the government—despite paying Armalite only $325,000 for the right to manufacture and market the AR-15. Colt’s position was that they took a chance on the AR-15. At the time they bought the rights to the weapon in 1959, it had already been rejected by the Army.

Right side view of a GM/Hydra-Matic M16A1. The last rifle was delivered in 1971. The rifles had type “D” buttstocks without trapdoors for storing a cleaning kit. ATF FIREARMS TECHNICAL DIVISION

Finally, on June 30, 1967, a contract was signed for the manufacturing rights and the Technical Data Package for the M16, M16A1 and XM-177 rifles, thus allowing the U.S. government to start the bidding for a second source to produce the weapons. Colt received a payment of $4,500,000 and a 5.5% royalty on all future weapons and parts procured by the government. During November of 1969, the XM-177 rifles were deleted from the contract agreement.

Initially there were 26 firms interested in a government contract to produce M16A1 rifles, but only 12 firms made bid deposits. After obtaining the Technical Data Package for review, only 8 remained interested in bidding. After intensive negotiations with the interested parties, GM’s Hydra-Matic Division and Harrington & Richardson (H&R) were awarded contracts. The decision immediately came under fire from members of Congress. The decision to use H&R was in question because of their marginal performance during their M14 rifle contracts. Hydra-Matic had manufactured the M39 20mm cannons, but had no experience with small arms. Bidders with successful small arms manufacturing experience like Saco-Lowell (who produced the M60 machine gun) and Cadillac Gage (who manufactured the Stoner weapon systems) were not chosen. The 65-member Source Selection Board making the decision felt that GM and H&R were positioned to get the urgently needed rifles in production the fastest.   

Manufacturer markings on
a GM/Hydra-Matic receiver. All Hydra-Matic serial num-bers were in the 3-million range. ATF FIREARMS TECHNICAL DIVISION

General Motors

During World War II, General Motors, better known as GM, had a long history of manufacturing military hardware by its many divisions. The hardware included, but was not limited to, ordnance, tanks, vehicles, machine guns, carbines and submachine guns.

The Hydra-Matic Division

General Motors’ Hydra-Matic Division was founded in May 1939 as the Detroit Transmission Division. It was created to continue the developmental work begun by Cadillac engineering and to manufacture the newly developed Hydra-Matic automatic automobile transmission. In 1962, the Division officially changed its name to the Hydra-Matic Division.

After the government procured the manufacturing rights for the M16A1 rifle, then Secretary of Defense, Robert McNamara, approved the Department of Defense’s plan to expand M16 production in March of 1968. Estimated ceiling prices with non-reoccurring startup costs were: first year production of 60,000 rifles at a cost of $316 each, second-year production 180,000 rifles at $105 each. The learning curve in the small arms industry was estimated to be 98%. The establishment of multiple sources for M16 production was not considered to be economically justified unless GM was at least 60% below the established ceiling price. Colt was producing M16A1 rifles at a cost of approximately $104 each.

Hydra-Matic upper receivers did not have any manufacturer or proof markings on them. Most had a “seam” or forging flash on the rear of the carry handle. INTL.MIL.CO

Hydra-Matic received a sole source, one-year contract, number DAAF03-68-C-0048, dated April 19, 1968, for 240,000 M16A1 rifles. Cost per rifle for the first contract was established at $151.54, well below the estimated ceiling price. The contract prices did not include the reoccurring cost of $8.68 for seven magazines or the $4,500,000 and 5.5% royalty paid to Colt for the rights to establish a second source production.

A GM plant in Ypsilanti, Michigan was chosen as the location for the manufacture of the M16A1 with the first deliveries to be during January of 1969. Production was to level off at 25,000 rifles per month. GM shipped the 100,000th M16A1 rifle to the Army two months ahead of the required schedule. It became apparent that GM/Hydra-Matic was proving capable of quality production ahead of schedule, while H&R was struggling with production and quality issues.

GM/Hydra-Matic upper receivers lacked any manufacturing markings in the concave area under the rear sight. The more common post-1970 Colt contract upper receivers were marked with two letters in that area. Another feature common of GM upper receivers is a rear sight windage dial with a distinctive number “3.” Note how the lower curve of the number 3 “droops.

A year later, the company had delivered another 140,000 rifles. On July 18, 1969, Hydra-Matic was awarded a second contract, DAAF03-70-C-002, for an additional 229,217 M16A1 rifles at a cost of $99.74 each. All the GM-produced M16A1 rifles were serial numbered in the 3,000,000 range.

Original GM/Hydra-Matic M16A1 rifles, manufactured over 50 years ago, are quite rare. There are not many original transferable U.S. Property marked Colt, GM or H&R M16 rifles in the NFA registry. Occasionally when they are offered for sale, the asking price is in the mid to high five-figure range. Buyer Beware: There are some M16 rifles in the NFA registry that were destroyed by the government and welded back together and registered prior to the cut-off date of May 19, 1986. An M16 with a receiver that was cut and welded back together would be priced considerably less than an original uncut one. An article describing the receiver welding process appeared in an old FIREPOWER magazine dated July of 1986, ironically published two months after the ban of the new registration of transferable machine guns.

Most GM/Hydra-Matic contract barrels were marked with the letters “MP” (magnetic particle inspected) between the front sight post legs. One of the rifles examined had the letters “MP” on top of the barrel between the legs of the front sight post. The barrels had chromium-plated chambers noted by a letter “C” on top of the barrel. The bores were not chromium-plated. ATF FIREARMS TECHNICAL DIVISION

The AR-15/M16 rifle has come a long way since it first appeared in the jungles of Vietnam. After a controversial and troublesome start, the rifle is now one of the most popular civilian semiautomatic firearms in the U.S. Currently, there are hundreds of companies offering numerous configurations of the AR-type rifle. Many younger AR aficionados don’t recognize the rifle in its original configuration. When seeing an original M16, they are often confused by its appearance and ask, “What is that; a carry handle?” With the widespread use of modern optics, the carry handle was removed from the design and replaced with a rail. High-tech optical devices also became a standard issue item in the U.S. military. There was a period where no commercial manufacturer offered an AR model with a carry handle, and soon the existence of the handle was unknown or forgotten.

Replica Retro Rifles

There has been growing enthusiast interest in AR/M16 rifles in their original as-issued Vietnam War guise fitted with the carry handle upper receivers, thin “pencil” barrels and triangle handguards. Many formerly obsolete original parts are sought after by individuals and many of the parts bring premium prices. Some of the rarest and difficult to find are those used in the M16A1 rifles made by GM’s Hydra-Matic Division and Harrington & Richardson, last manufactured in the early 1970s. Most of the M16A1 rifles from that era were given away as military aid or scrapped, making the parts difficult to find.

Letter “G” mark on a GM/Hydra-Matic M16A1 hammer, the number “3” inside the “G” is to identify the subcontractor who manufactured the part. INTL.MIL.CO

The assembly of a “correct” GM/Hydra-Matic replica rifle can be quite expensive. When building a Vietnam-era copy the quest for an all-original clone usually ends at the lower receiver; most must settle for using a modern replica semiautomatic receiver. There are a few companies that will duplicate the GM/Hydra-Matic and U.S. Property markings by laser engraving, or roll-marked like the originals were. Most of the available receivers found today are the later reinforced M16A2 design—to be “correct” an M16A1 style lower receiver should be used.

A less expensive alternative to using hard-to-find, expensive original parts for a retro build are reproduction parts from companies like Brownells, NoDak Spud, AR15sport.com and JSEsurplus.com, to name a few.

A GM/Hydra-Matic trigger with a number “2” inside the letter “G.

Identifying GM/Hydra-Matic Parts

Original GM/Hydra-Matic and H&R M16A1 parts occasionally surface, knowing how to identify them is key. During the research for this article there were four original GM/Hydra-Matic M16A1 rifles studied, and several internet resources, used as an attempt at identifying parts used in the assembly of GM/Hydra-Matic M16A1 rifles.  

There are certain features that are common to most Hydra-Matic manufactured M16A1 rifles; with the small fraction of the weapons available for examination it is not possible to make statements using the word “all.” The attrition rate of 50-year-old Vietnam era M16 rifles, arsenal rebuilding and repair of weapons in the field by armorers, and the large number of subcontractors suppling parts make definitive identification impossible. That said, observations made by the authors and others have concluded the following are common characteristics of M16A1 rifles made by GM/Hydra-Matic.

It is quite likely that many subcontractors were used by GM during the production of their M16A1 rifles. Some of the similar markings on some parts common to GM and H&R rifles suggest that they may have used some of the same subcontractors.

There are several ways to ID GM/Hydra-Matic parts from those from H&R and the far more common Colt parts. Many GM parts are marked with a number, most likely to identify the subcontractor who made the part.

Mottled GM/Hydra-Matic pistol grip. GM pistol grips were slightly larger in circumference than Colt M16 grips. INTL.MIL.CO
Rear side of a GM contract fire selector, with a number “1” inside the letter “G.

Lower Receiver

The finish color on GM/Hydra-Matic rifles varies, many are darker in color than the 1960s era Colt’s gray. Hydra-Matic Div., G.M. Corp. U.S.A. Property U.S. Govt marked on the left side of the magazine well. On the right side there is a full “fence” around the magazine release, and often a white 1-inch DoD eagle acceptance stamp that is larger than those found on Colt and H&R rifles.

Bolt Stop

GM contract bolt stops have a subcontractor ID number on the bottom. Numbers 1 through 7 have been noted. Bolt stops marked with a number “3” are common.

Upper Receiver

There are variations of the upper receivers documented, one common sign is the lack of markings in the concave area on the right side under the rear sight. Colt contract upper receivers made after 1970 will have two letters in that area. GM upper receivers will generally have a forging flash, or “seam,” on the rear of the carry handle. The front lug is recessed on the left side. The forward assist will have a number on the back side of the teardrop handle. The ejection port door with have a small pad with rounded corners. Any wear of the anodized finish will reveal a yellow-gold color. H&R uppers typically have a forging flash on the front and rear of the carry handle and the rear sight direction arrow is usually different. They often have the same style ejection cover door.

Notes:

  • Rifle 3018041 upper receiver no forge seams
  • Rifle 3027458 upper receiver no forge seams
  • Rifle 3136345 upper receiver forge seam on rear only
  • Rifle 3245701 upper receiver no forge seams
GM/Hydra-Matic receiver remnant destroyed by shearing it in several pieces—a fate suffered by most M16 and M16A1 rifles manufactured during the Vietnam War. PRIVATE COLLECTION

Charging Handle

GM contract charging handles will have six punch marks, or dots, across the back of the handle and have a slightly thinner profile.

Fire Control Group

The fire control components, hammer, trigger and fire selector lever will have a stylized letter “G” with a number inside. The disconnector was not marked. The mode of fire selector levers were marked on the rear surface. Keep in mind that using M16A1 fire control group parts in a semiautomatic AR rifle can cause legal problems. It is strongly suggested that any M16 internal parts be altered to a semiautomatic configuration.

Barrel

The GM barrels with have the letters “MP” on the rightside between the legs of the front sight base. There will be a letter “C” on the top of the barrels indicating chrome chamber. Barrels are the .625-inch outside diameter “pencil” type with a 1:12 twist, and a “birdcage” flash hider. Original barrels are probably the most difficult component to find, many M16 rifles had to be re-barreled due to excessive use and / or corrosion of the bores. Original barrels, front sight blocks and flash hiders typically have a rougher finish machining than those found on Colts. Colt and other contractors made thousands of replacement barrels during the Vietnam War. During 1967, there was a projected demand of 11,800 barrels per month. Note: one of the GM rifles examined, serial number 3018041, had the “MP” mark on top of the barrel under the front sight base.

A GM/Hydra-Matic receiver recovered from a damaged M16A1 after a suicide bomber det-onated a truck bomb at a building housing the 1st Battalion 8th Marines in Beirut, Leba-non. Killed in the October 23, 1983 attack were 220 Marines, 18 sailors and 3 soldiers. BRUCE ALLEN, USMC NATIONAL MUSEUM
GM contract furniture can be identified by a raised “cross” symbol like the one inside of this GM pistol grip.

Front Sight Base

There are several front sight base variations. Some have forging flash on the front and/or rear, and on the bayonet lug. Some bases observed had a forging code letter or number on the sides and on the lug for the bayonet. Some are not marked with any codes. None of the rifles examined had any visible markings on the front sight base.  

Furniture

Most were fitted with “type D” buttstocks, without trapdoors, a rubber buttplate and a moveable sling swivel. The furniture often has an aged “mottled” appearance. The “fat” pistols grips have a slightly larger circumference than those fitted on Colt M16 rifles. GM pistol grips, handguards and buttstocks will have a raised cross symbol on them, letters and numbers have been observed in various locations. Buttplate screws have a drain hole drilled through the center. Triangle handguards secured with a flat slip ring.  

Bolt Carrier and Bolt

GM/Hydra-Matic bolt carriers do not have any manufacturer’s markings; the finish machining appears rougher than on most Colt bolt carriers. The GM bolts were marked “MP” to indicate that they were magnetic particle inspected. The marking is very similar to Colt’s, but the “MP” letters are connected on the GM.

GM/Hydra-Matic handguards, pistol grips and buttstocks will have a raised “cross” symbol molded on them.

Buffer

The buffer will usually have a dimple on the front and an orange or maroon color pad (possibly discolored with age).

Sling

The sling issued during the Vietnam War was the mildew-resistant nylon sling with cadmium plated hardware. Front and rear sling swivels on all GM/Hydra-Matic rifles were secured with roll pins.

GM/Hydra-Matic Rifles Used for Study

Courtesy of ATF’s Firearms Technical Division. Serial numbers: 3245701, 3018041, 3136345, 3027458. Special thanks to Eve Eisenbise, Anthony Ciravolo and Jeff Bodell (ATF FATD).

A GM/Hydra-Matic M16A1 lower receiver in the “white.” Note that the receiver does not have a serial number. ATF FIREARMS TECHNICAL DIVISION
Retro GM and H&R clone M16A1 rifles. INTL.MIL.CO

Resources

Government Documents (Declassified)

  • Procurement, Production and Distribution of the AR15, M16 and M16A1 Weapon System (1 June 1968)
  • Procurement History and Analysis of the M16 Rifle (Printed 2 Aug 71)
  • M16A1 Initial Production and Comparison Test; GM. H&R, Colt. (9 Jan 69)
  • M16A1 Rifles, Hydra-Matic- collection of Amendments to the original contract and correspondence 1968-1971, on the General Motors Corporation Hydra-Matic Division M16A1 contracts. English Language. (Courtesy Dan Shea, Small Arms Review Reference Library)

Books

  • The Black Rifle: M16 Retrospective R. Blake Stevens and Edward C. Ezell
  • The Great Rifle Controversy Edward Clinton Ezell  
This article first appeared in Small Arms Review V25N8 (October 2021)
Tags: 2021Chris CoxForgotten M16A1 Rifle ManufacturersFrank IannamicoGM/Hydra-Matic and Harrington & RichardsonOCTOBER 2021Part IV25N8
Previous Post

Revision Moves Upmarket with New Speed Demon Metal Sunglasses

Next Post

Helix 6 Precision Announces SIG Cross Factory Prefit Barrel Line

Next Post
Helix 6 Barrel with Cross Rifle

Helix 6 Precision Announces SIG Cross Factory Prefit Barrel Line

TRENDING STORIES

  • U.S. NAVY MK18 MOD O CUSTOM CLOSE QUARTER COMBAT WEAPON FOR THE SEAFARING SERVICE

    U.S. NAVY MK18 MOD O CUSTOM CLOSE QUARTER COMBAT WEAPON FOR THE SEAFARING SERVICE

    0 shares
    Share 0 Tweet 0
  • Recreational Use Of 40MM Grenade Launchers

    0 shares
    Share 0 Tweet 0
  • Customizing the Already Custom SIG P320 Spectre Comp

    0 shares
    Share 0 Tweet 0
  • Col. Rex Applegate: The Knife Designs of a Close-Combat Legend

    0 shares
    Share 0 Tweet 0
  • Evolution of the U.S. Grenade Launcher From World War II to Today’s Conflicts

    0 shares
    Share 0 Tweet 0
  • Trending
  • Comments
  • Latest
U.S. NAVY MK18 MOD O CUSTOM CLOSE QUARTER COMBAT WEAPON FOR THE SEAFARING SERVICE

U.S. NAVY MK18 MOD O CUSTOM CLOSE QUARTER COMBAT WEAPON FOR THE SEAFARING SERVICE

Recreational Use Of 40MM Grenade Launchers

Recreational Use Of 40MM Grenade Launchers

SIG Spectre Comp with AXG Grip Module

Customizing the Already Custom SIG P320 Spectre Comp

Col. Rex Applegate: The Knife Designs of a Close-Combat Legend

Col. Rex Applegate: The Knife Designs of a Close-Combat Legend

New Review: V19N1

New Review: V23N3

SAR|Special

SAR|Special

The Grand Power Q100

The Grand Power Q100

A Fading Star: The star S135 Submachine Gun, That is

A Fading Star: The star S135 Submachine Gun, That is

Meet T.E.D.D.: Weapon of Mass Distraction

Meet T.E.D.D.: Weapon of Mass Distraction

The Italian Job: Beretta’s P71 Pistol

The Italian Job: Beretta’s P71 Pistol

The Nambu Type 94 – A Basic Treatise on the Worst Combat Handgun in Military History

The Nambu Type 94 – A Basic Treatise on the Worst Combat Handgun in Military History

Situational Awareness: Getting off the “X”

Situational Awareness: Getting off the “X”

QUICK LINKS

  • About Chipotle Publishing
  • About Small Arms Review
  • Advertise with Us
  • Write for Us

CONTACT DETAILS

  • Phone: +1 (702) 565-0746
  • E-mail: office@smallarmsreview.com
  • Web: www.chipotlepublishing.com
  • Chipotle Publishing, LLC 631 N. Stephanie St., No. 282, Henderson, NV 89014
Small Arms Review

FOLLOW US

  • Privacy Policy
  • Disclaimer

© 2022 Chipotle Publishing | All Rights Reserved

No Result
View All Result
  • Home
  • Articles
    • Guns & Parts
    • Suppressors
    • Optics & Thermals
    • Ammunition
    • Gear
    • News & Opinion
    • Columns
    • Museums & Factory Tours
    • ID Guides
    • Interviews
    • Event Coverage
    • Articles by Issue
      • Volume 1
      • Volume 2
      • Volume 3
      • Volume 4
      • Volume 5
      • Volume 6
      • Volume 7
      • Volume 8
      • Volume 9
      • Volume 10
      • Volume 11
      • Volume 12
      • Volume 13
      • Volume 14
      • Volume 15
      • Volume 16
      • Volume 17
      • Volume 18
      • Volume 19
      • Volume 20
      • Volume 21
      • Volume 22
      • Volume 23
      • Volume 24
  • The Archive
    • Search The Archive
  • Store
    • Books
    • Back Issues
    • Merchandise
  • Podcast
  • Newsletter
  • Events
  • FrankenGun Challenge
  • About
    • About Small Arms Review
    • About Chipotle Publishing
    • Contact Us
    • Other Publications
      • Small Arms Defense Journal

© 2022 Chipotle Publishing | All Rights Reserved

Welcome Back!

Login to your account below

Forgotten Password?

Retrieve your password

Please enter your username or email address to reset your password.

Log In

Add New Playlist

This website uses cookies. By continuing to use this website you are giving consent to cookies being used. Visit our Privacy and Cookie Policy.

Subscribe To Our Weekly Newsletter

Are you in the know?
Stay up to date with the latest articles.

Facebook-f Linkedin Instagram

Redirecting to External Website

You are leaving the Small Arms Review website and will be redirected to an external link in a 5 Seconds.
VISIT NOW!