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GM-M51 16" M4 Barrel Assembly 1:7 twist

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Product Description

5.56 mm, 1:7 twist, 16" long, 41V50 steel, weighs 2.0 lbs, button rifled, air gauged, stress relieved,  it is already assembled with an A2 Front sight Base, Post, Detent, and Spring, a Handguard cap, and Barrel Nut. The GM-M51 sports a Carbine Gas length, M4 Feed ramps, chrome line bore and chamber,  phosphate exterior coating.

For a Limited Time, the NEW GM-M51!

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Product Reviews

Previous | Showing reviews 6-10 of 11 | Next

  1. Follow up 5 Star Review

    Posted by on 22nd Mar 2018

    I purchased this barrel 08/17 and after a few thousand rounds decided to do a follow up review.
    The barrel has performed perfectly. The important things like accuracy and durability has been exceptional. Will I buy another...Absolutely. I gave it 5 stars because as a trusted barrel, it is, M4 feed ramps were perfectly aligned and the head-spacing was perfect with my bolt.
    As a former Marine and a 25 year retired LEO, I don't gamble with faith or luck, my build was purely for home defense, the protection of my family. So of course I went with quality, not hype.
    The only two things I would change, for what my opinion is worth, is an "F" marked FSB, I had to order a .040 height sight post to sight in with my
    MBUS, and the second really minor bitch...The engraving on my barrel was double and lightly stamped, (5.56 NATO) so it was unreadable.

  2. Just what I was looking for 5 Star Review

    Posted by on 20th Feb 2018

    I set out to build an M4 look-alike rifle with the A2 frond sight post and the A2 carry handle. Little did I know that the A2 sight post/gas blocks are so hard to come by. This was exactly what I was looking for in a barrel, complete with the A2 sight, and it's from GMRB so I knew from previous experience it's work great. Fits wonderfully on the new build and couldn't be happier. Great shooter too. Thanks GMRB!

  3. Wow! 5 Star Review

    Posted by on 22nd Oct 2017

    I bought this barrel the 2nd week it came out and have about 500 rounds of green tip 62g federal through it. I shoot anywhere from 50-150 yards and the groups a just as tight as my bcm barrel. I’m super happy with it and will forever go with Green Mountain Barrels!

  4. The best barrels you can buy without having sell a kidney. 5 Star Review

    Posted by on 9th Oct 2017

    This is the 3rd barrel I've bought and once again I'm not disappointed. They have a great life span and accurate as anything else.

  5. Great Barrel 4 Star Review

    Posted by on 13th Sep 2017

    A great barrel for my M4 build. It's worked great. All the specs were what I wanted. The only thing I wish was different is the FSB. It's an A2 FSB, not "F" marked. I knew this, and still thought the barrel was a great buy. I do wish going forward, they would have an "F" marked FSB, as that is the standard for a carbine build. Still, love the barrel.

Previous | Showing reviews 6-10 of 11 | Next