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 Articles Articles by Issue Volume 16 V16N3 (3rd Quarter 2012)

PWS MK 112: A LONG STROKE AR SBR

SAR Staff by SAR Staff
September 14, 2022
in V16N3 (3rd Quarter 2012), Articles, Articles by Issue, Guns & Parts, Optics & Thermals, Search by Issue, Volume 16
PWS MK 112: A LONG STROKE AR SBR
Share on FacebookShare on Twitter

By Todd Burgreen

Of late, the attention seems to be focused on “improving” the AR platform via developing piston-driven ARs in lieu of Stoner’s original gas-impingement design. Whether or not piston-driven ARs are superior to their gas impingement brethren often generates heated discussion debating the pros and cons of each AR operating method. Within the piston-driven AR family there are various operating methods employed with no standardization of parts arrived at as of yet. This leads us to Primary Weapons Systems’ (PWS) contribution to the AR field with its MK 1 series of long-stroke piston operated ARs compared to the more common short-stroke method found in other manufacturers’ designs.

PWS literature clearly lays out the thought process behind the development of the MK 1 series with their fascination with the simplicity and reliability of the AK47 combined with a deep-rooted appreciation for the ergonomics of the M4/M16 platform and seeks to maximize the 50-year old AR design in terms of reliability and operating efficiency. PWS is confident that the MK 1 is an improvement over not only the original gas impingement design, especially when incorporated into short barrel platforms, but also other piston AR designs featuring short stroke pistons. Significant changes are present in the MK 1 PWS compared to both the direct impingement operating system and other piston-driven operating systems. PWS product improvements address reliability and performance issues as well as reduced carrier tilt, cam pin wear and carrier bounce.

PWS MK 112 upper with Leupold VX-R Patrol optic mounted with a Leupold base. The PWS MK 112 represents the ìsweet spotî of sub-16 inch handling while maintaining some semblance of rifle ballistics and terminal performance.

The PWS upper tested herein, the MK 112, features a 12.5 inch barrel and was mated to multiple registered AR lowers, including a select fire version. One of the major differences found in PWS products is its utilization of a long stroke piston system. While there are a variety of definitions ranging from technically complex to simplistic of what exactly long stroke and short stroke consists of; for our purposes, long stroke is exemplified by the AK47 method of having op rod connected to the bolt carrier whereas short stroke consists of a more complicated arrangement of tapped gas imparting force to an op rod that impacts another part of the mechanism that acts on the bolt carrier. The MK 1 series has been used in Iraq and Afghanistan, and has gained wide popularity with private security personnel, law enforcement and civilians alike.

The MK 112 is a natural for CQB/Direct Action roles signified by its shorter than normal barrel length of either the standard M16 or M4 rifles. The 12.5 inch barrel represents the optimum cross-breeding of handling to cartridge performance. The MK 112 PWS produces approximately 2,800+ fps velocity with the 55gr/62gr 5.56mm round while still offering compact handling and enough rail space for solid purchase and accessory additions as mission dictates. A proprietary PWS hand guard system utilizes and features a non-free float panel system that allows the end user to replace individual rails as needed without removing the barrel, barrel nut or even other rails. Imagine if you will, the PWS gas/piston tube surrounded by rails that do not rely on being attached to the tube; rather the rails are attached at the pinned gas block in the front and the receiver at the rear. The design facilitates better air flow around both the gas tube and barrel for more efficient cooling during long strings of fire. This does not mean that the MK 112’s handguards do not get hot. This is a natural result of the operating rod location running down the length of the handguard to the action and not untypical for long stroke designs which utilize the muzzle gasses to operate the piston. Gloves, small vertical forward grip, and rail panels provided with the PWS MK 112 are necessary if any volume of fire is expected. The MK 112’s user can attach numerous devices such as sights, lights, vertical forward grip and laser aiming devices.

The PWS MK 112 was evaluated at Echo Valley Training Center. The private facility has multiple 100 yard berm-enclosed bays capable of handling numerous students conducting “square” range drills or more dynamic/fluid types of training. In conjunction with the individual training bays, Echo Valley Training Center features multi-stepped target berms that are strewn with reactive steel targets, fluid drained automobiles, and moving targets at ranges varying from 150 yards out to 350 yards.

The key with the PWS MK 112 is having a 12.5 inch barreled AR that works and functions at the same reliability level as longer barrel ARs. This is where the PWS long stroke piston comes into play. The PWS system utilizes an operating rod that is attached to the carrier and a floating head piston that is attached to the operating rod. The MK 1 series is built to be a true combat carbine. With no unnecessary gas adjustments and only one moving assembly, proponents point to the MK 1 as the most rugged, simple and versatile piston operating system available. The MK 1 series is available as a complete carbine or rifle or as a “drop-on” upper receiver for use on the lower receivers of existing M4/M16 style lowers, which is the path chosen for this review.

The PWS MK 112 installed on a lower combines to weigh 6.5 pounds and has an overall length of 29.5 inches with adjustable stock extended. The MK 112’s stainless steel button rifled Isonite treated 12.5 inch barrel features 1:8 twist. The 1:8 twist was selected to accommodate the widest variety of 5.56/.223Rem loads. A PWS Triad flash suppressor was fitted on the MK 112’s barrel. PWS designed the Triad specifically to address the notorious muzzle flash associated with short barreled rifles.

The PWS MK 112 was evaluated at Echo Valley Training Center. The private facility has multiple 100 yard berm-enclosed bays capable of handling numerous students conducting “square” range drills or more dynamic/fluid types of training. In conjunction with the individual training bays, Echo Valley Training Center features multi-stepped target berms that are strewn with reactive steel targets, fluid drained automobiles, and moving targets at ranges varying from 150 yards out to 350 yards.

PWS long stroke op rod connects directly to the bolt carrier group. PWS product improvements address reliability and performance issues as well as reduced carrier tilt, cam pin wear and carrier bounce. PWS seeks to maximize the 50-year old AR design in terms of reliability and operating efficiency.

It was decided to take full advantage of the MK 112’s flattop upper and performance represented in the 12.5 inch barrel by mounting a newly introduced Leupold optic – the VX-R Patrol with illuminated reticle. The VX-R Patrol is available in both a 1.25-4x20mm model with the FireDot Special Purpose Reticle and 3-9x40mm with TMR FireDot reticle. The Leupold VX-R with FireDot SPR reticle is designed for instinctive, close-range/low-magnification situations, yet allows shooters to engage targets with greater precision at longer ranges than generally possible with non-magnified red optics or other reticle style low powered scope. The Leupold VX-R 1.25-4x is an optic candidate worthy of being left on the PWS MK 112 full time. It is able to handle multiple roles as a user decides albeit close range engagements or further. The Leupold VX-R offers the capability to engage multiple targets in rapid sequence due to its FireDot reticle pulling the shooters eye to the aiming point, while at same time providing adequate accuracy out to a couple hundred yards. As many “maturing” shooters can attest to, the single focus plane is easier to shoot accurately than coordinating front and rear sights. The 5.56/.223’s flat trajectory aids in making hits out to 250 yards without having to compensate excessively for bullet drop with the short 12.5 inch barrel proving not that much of a hindrance to velocity; A 200 yard zero provides for +2 inches at 100 yards and -13 inches at 300 yards.

Comparison of PWS MK 112 size next to a PWS MK 107 Diablo 7 inch barrel and 20 inch heavy barreled AR upper. The MK 112 maintains rifle ballistics compared to the Diabloís more SMG like performance.

Ammunition tested with the PWS MK 112 was a combination of Black Hills Ammunition loads, Federal Premium Law Enforcement 55gr Triple Shok and 62gr Bonded SP loads, Wolf 55gr FMJ, and Winchester 55gr FMJ. The MK 112 kept all loads tested under 2 inches at 100 yards with the Federal Premium 55gr Triple Shok and Black Hills 69gr Match producing near MOA groups out to 200 yards. Overall, the accuracy level was more than acceptable considering the barrel’s profile. Accuracy test protocol consisted of five three-shot groups with each ammunition type; group sizes were averaged. Velocity figures ranged from 2,800-2,900 fps over a RCBS chronograph.

C.R. Newlin, Echo Valley Training Center owner and partner in Stonewall Arms, generously allowed me to borrow his select fire AR lower for testing with the PWS MK 112. Range testing commenced with functionality tests consisting of dumping multiple magazines at several targets in rapid fashion once sight zeros were verified. Any fighting rifle must be reliable to be worthy of further consideration. The importance of quality magazines can not be overstated in terms of impacting a weapon’s reliability. The majority of malfunctions in a select fire, or even semi-auto rifle, can be traced to a faulty magazine. I primarily use Brownells’ AR magazines for this reason, though random magazines are mixed into testing at times. The PWS MK 112 long stroke gas piston operating rod system proved its worth in keeping the bolt carrier group cooler and cleaner compared to direct impingement AR rifles. While not trying to be unrealistic or overly harsh, the PWS MK 112 was exposed to multiple magazine dumps at various times of the T&E. The method was not mindless ammunition wasting, but rather wanting to confirm beyond a doubt that the PWS MK 112 was reliable under the most extreme circumstances. Along these lines, recoil and muzzle climb was found to be less than expected even when firing on full automatic.

The PWS MK 112 was used during portions of Jason Fallaís Redback One Tactical Carbine course. A US Palm Multi-Platform Attack Rack chest rig was found to be an ideal platform to support the PWS MK 112. It can accommodate up to five 30-round M4 magazines or up to five 20-round .308 magazines or any other combination of magazines and accessories you may need with a 2×14 MOLLE attachment spanning the exterior. The bottom of the carrier allows access to the custom level IIIA soft armor panel or the adding of a hard SAPI plate.

One of the lowers used with the PWS MK 112 upper contained a patented Wilson Combat Tactical Trigger Unit (TTU). It is simple to install by anyone with rudimentary AR maintenance skills and instantly enhances shooter-to-rifle interface. Wilson Combat designed the TTU not as a match trigger, which can be less than hardy under robust conditions, but rather as single stage 3.5-4.0 lb. trigger with a short reset suitable for all conditions of use. The Wilson Combat TTU requires no field adjustment and does not have any loose parts or screws that seem to come loose at the worst time. The TTU hammer geometry was designed with military/surplus primers in mind allowing for reliable ignition of all ammunition. The Wilson Combat TTU meets or exceeds military specifications for drop safety – something that “match” triggers usually can not represent as doing. All in all, the Wilson Combat TTU allows for multiple rounds to be sent downrange quickly/accurately and for precise longer range shot placement better than your standard trigger unit; yet retains reliability lacking from some of the other trigger units on the market.

An even better evaluation of the PWS MK 112 was its use in portions of Jason Falla’s Redback One Tactical Carbine Course conducted at Echo Valley Training Center. It got exposed to realistic training curriculum during multiple exercises involving quick reaction shooting, multiple rounds on several targets, moving while shooting, and working around barricades. Team Tactic exercises involving moving to and from a designated target area using cover while either changing magazines or engaging targets when a partner is reloading are other good weapon evaluation drills. One gets a good sense of the way a weapon handles along with reliability due to the sum of ammunition expended in short time frames characteristic of these Team Tactic drills.

The 5.56/.223ís flat trajectory aids in making hits out to 250 yards without having to compensate excessively for bullet drop with the short 12.5 inch barrel proving not that much of a hindrance to velocity; a 200 yard zero provides for +2 inches at 100 yards and -13 inches at 300 yards. Velocity figures for the MK 112 and ammunition tested ranged from 2,800-2,900 fps over a RCBS chronograph.

The PWS MK 1 gas-piston system can be disassembled for maintenance without requiring the rifle’s handguards to be removed, unlike some of the short stroke ARs on the market. Cleaning methods for the PWS MK 112 are familiar to anyone with experience with the AR-15. The PWS long-stroke gas system serves to isolate the action from heat and fouling, especially when compared to the typical AR direct gas impingement method of dumping gas directly into the action.

The BATF regulations of what constitutes a rifle compared to a NFA SBR (Short Barrel Rifle) weapon as pertaining to barrel length serves as an artificial threshold for barrel length on civilian rifles. As can be imagined, most consumers are content to go with the 16-inch barrel to avoid onerous paperwork and tax stamp fee associated with a less than 16 inch SBR rifle even if a shorter barrel is better suited for the task intended. Some may question the utility of employing a rifle with a barrel measuring 12.5 inches. Is the 3.5 inches worth the non-NFA 16 inch version? That is a question each individual will have to answer. The fact is that most engagements happen well within a 100 yard range, especially in law enforcement or civilian settings, with handling and reliability playing more of a factor in quick, reactive engagements than muzzle velocity. However, the RCBS chronograph indicates that only approximately 200 fps is lost with the MK 112’s 12.5 inch barrel. A 7 inch PWS MK 107 Diablo upper was test fired with similar ammunition for comparison sake with the PWS MK 112. The 7 inch barrel produced velocities in the 2,300 fps range – really showing the advantage represented by the MK 112’s longer barrel in terms of velocity. The PWS MK 112 represents the “sweet spot” of sub-16 inch handling while maintaining some semblance of rifle ballistics and terminal performance.

he PWS MK 112 kept all loads tested under 2 inches at 100 yards with the Federal Premium 55gr Triple Shok and Black Hills 69gr Match producing near MOA groups out to 200 yards. The group shown here was at 100 yards.

Sites of Interest:

Primary Weapons Systems

(208) 344-5217
www.primaryweapons.com

Black Hills Ammunition
(605) 348-5150
www.black-hills.com

Echo Valley Training Center
www.echovalleytrainingcenter.com

ATK/Federal Cartridge Company
(800) 322-2342
www.federalpremium.com

Leupold & Stevens Inc.
www.leupold.com

Brownells’ Inc.
(800) 741-0015
www.brownells.com

This article first appeared in Small Arms Review V16N3 (September 2012)
Tags: 20123rd Quarter 2012PWS MK 112: A LONG STROKE AR SBRSEPTEMBER 2012Todd BurgreenV16N3
Previous Post

THE FN SCAR 16 CIVILIAN SCAR

Next Post

TO ANNEAL OR NOT TO ANNEAL

Next Post
TO ANNEAL OR NOT TO ANNEAL

TO ANNEAL OR NOT TO ANNEAL

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

The Iron Door: Soviet Russian Weapons Designers Stop the Germans in Their Tracks

The Iron Door: Soviet Russian Weapons Designers Stop the Germans in Their Tracks

The American FN FAL Rifle: In Search of the Perfect Lightweight Rifle

The American FN FAL Rifle: In Search of the Perfect Lightweight Rifle

Ahead of Its Time: British Fosbery Pump-Action Shotgun with “Stoner” Bolt

Ahead of Its Time: British Fosbery Pump-Action Shotgun with “Stoner” Bolt

The Big Bang! : Great American Fun at the 2018 Big Sandy Machine Gun Shoot in Wikieup, AZ

The Big Bang! : Great American Fun at the 2018 Big Sandy Machine Gun Shoot in Wikieup, AZ

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!