Loading... Please wait...

Like Us on Facebook!


Add to Wish List

Click the button below to add the GM-M8 16" 5.56x45mm 1:8 Twist to your wish list.

You Recently Viewed...

GM-M8 16" 5.56x45mm 1:8 Twist


Product Description

  • Caliber- 5.56x45mm
  • Twist- 1:8
  • Length- 16"
  • Profile- Government Under "See 1 more picture" there is a detailed drawing of this barrel.
  • Finish- Chrome Lined Phosphate
  • Gas System Length- Mid
  • Gas Block OD- .750+-(.001)
  • Steel Type- 41V50
  • Thread Pitch- 1/2x28
  • Weight- 1.85lbs

Write your own product review

Product Reviews

Showing reviews 1-5 of 68 | Next

  1. Kind-of a huge let down 2 Star Review

    Posted by on 17th Apr 2021

    Forward: all groups were limited to 5rnds due to shortage, and ammo most commonly used was independence 55gr made by IMI.

    After everything I'd read about these barrels I was quite excited to take mine out and shoot it, unfortunately however it turned out to be a big downer. Using a 6 power scope I could barely get it down to 4moa, the same as I shot that day with irons on my a2 using the same ammo (unfortunately I don't shoot often at all, so it wasn't a case of me being as good with irons as the scope). Thinking it might be the ammo I took out some open tip match mk318 rounds I had been saving back, unfortunately though that didn't help as it liked those even less, 6.5-7.5moa. I got the gun sighted in I suppose, but it was pretty dissapointing to see how my new barrel did, then pick up my a2 and match it; the biggest kicker came later in the shooting session when I shot the same ammo through my brothers psa with one of their nitride barrels and had it hold a consistent 2.5-3moa. I don't doubt what others have said about their experiences, but I personally will likely be hesitant to purchase more green mountain barrels in the future.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

Showing reviews 1-5 of 68 | Next