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GM-M8 16" Mid Length gas system 5.56 mm


Product Description

5.56mm, 1:8 twist,16", 41V50 steel, weighs 1.9 lbs., mid length gas system, chrome line bore and chamber, phosphate finish, button rifled, stress relieved, air gauged, gas port, assembled with M4 extension with M4 feed ramps, muzzle thread 1/2 x 28. 

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Product Reviews

Showing reviews 1-5 of 67 | Next

  1. Simplistic Perfection 5 Star Review

    Posted by on 18th Sep 2020

    Should be the standard for all military barrels going forward. Most important thing to note is the twist rate. The one and eight twist rate allows to stabilize everything from 55 grain to 75 grain ammo. Without any degradation of accuracy.

  2. Best Bang for your buck barrel 4 Star Review

    Posted by on 26th Aug 2020

    Incredibly accurate, feeds whatever I throw into it from cheap and old steel case wolf up to IWI match ammo. No noticeable wear on the feed ramps and lug slots even after 1K rounds of steel case in one range outing. Green Mountain has a reputation for their .22LR barrels, and the same level of machining precision and shooting accuracy can be found in this barrel.

    Why only 4 stars then? No dimples on the underside of the gas block area, and a mid-length gas system means the handguard gets HOT right where I like to grip it. The lack of dimples is fine, just a little annoying for initial install. Just remember to loctite your gas block set screws.

  3. Excellent Barrel and Customer Service 5 Star Review

    Posted by on 7th Apr 2020

    I was told about Green Mountain Barrel Co about 3 or so years ago. At the time I was taking my armorer's courses and the instructor, who was the very particular type, told me GMB makes really nice barrels. I didn't know GMB at the time but trusted the instructor for a number of reasons.
    I bought my 1st from them and was extremely pleased. I bought this barrel next for a truck gun build. The price should be higher on these barrels, especially considering what the industry overall is outputting for similar prices. GMB ships fast and accurate and provides excellent communication concerning your order. I gauged, inspected and bore scoped both barrels and they were flawless. The headspace, chamber, gas port, crown, and straightness all checked out within spec with the gauges. The finish is uniform and the barrels are well marked. Both were made mid-length 16" barrels. They are easy shooters, not over gassed and are accurate. I will buy again and I would absolutely recommend for anyone who is seeking a quality barrel. I am not a fan of nitride/melonite/QPQ treated barrels because most are not made properly, many seem to not pass gauges for one reason or another, the treatment can impact the steel's tempering negatively, and I've seen too many suffer the common problem of barrel extensions coming apart from the barrel. They are cheap and the biggest benefit is to those manufacturers that make them rather than the shooter buying them. They open the window to many potential issues. Not to mention the top barrel manufacturers and the military have steered clear of it for it's issues. For that reason I like a chrome lined barrel. People can get sucked into nitride for low price and claims of high round counts and supposed increased accuracy over chrome. A quality barrel is a quality barrel and a quality barrel will be an accurate barrel - without all the potential issues. This is exactly what Green Mountain Barrel Co delivers and they're doing it at a high value price point.

  4. Glad I bought this 4 Star Review

    Posted by on 11th Mar 2020

    On a quest for a high quality, highly accurate rifle, this is a very nice option.

  5. Perfect 5 Star Review

    Posted by on 28th Oct 2019

    I read all the good reviews on the forums about this barrel, and decided it was worth the chance...especially for the price point. Got it installed, and sure enough...sub moa at 100 with 77gr match ammo. Decided to stretch its legs, and put round after round on a 12x12 steel plate at 500 yards. So easy it was boring. This isnt some match rifle either...its a base m&p sport, with free float handguard and a 2.5-15 scope. Very impressed!!

Showing reviews 1-5 of 67 | Next