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GM-B5 17"Chambered Gunsmith Edition 300 Blackout 1:7 twist


Product Description

  • Caliber- 300BO/ 7.62
  • Twist Rate- 1:7
  • Length- 17"
  • Profile- Chambered barrel blank
  • Steel Type- 41V50
  • Weight- 4.00lbs

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Product Reviews

Showing reviews 1-5 of 6 | Next

  1. Excellent quality for a gunsmith ready part 5 Star Review

    Posted by on 12th Jan 2021

    The barrel chamber look to be free from defects, and the bore is clean, pristine, straight according to my optical test, and the bore is centered in the blank. Exterior is darn near finish quality if you want a heavy barrel, although the gas block would need to be a custom size.

  2. Top Shelf 5 Star Review

    Posted by on 20th May 2019

    There is no satisfying way to exemplify the extent of quality and results in accuracy I have obtained with this .300BLK, and the 5.56 chambered blanks also.
    Quite frankly I had no idea what accuracy is in an AR platform till getting these chambered blanks and finishing them.
    First machined the .300BLK for a 14.5 inch barrel. This set up, with a .110 diameter gas port shoots Hornady Black 110 grain Amax rounds, better than I can shoot let me tell you!
    The latest .300 BLK chambered blank is on a 10 inch pistol AR.

    The 14.5 inch is such a wonderful brush gun for deer hunting I'm going for it, put a Trijicon 1-4 Accupoint, with the tritium & fiber optic green triangle reticle.
    I'll hunt with this rifle till that day I take a dirt nap.
    Under 200 yards it is a deer hammer you put a round in the ticker. And flat shooting with the .110 grain bullets, 3.5 high at 100 yards gives you a perfect 200 yard zero. In thse WV mountains 200 yards is a long shot, so it is the perfect carbine for me.

    I can not recommend enough you get yourself one of these chrome lined chambered blanks, with the high vanadium 4140 alloy. All have head spaced right on the money. They blue up real nice with Brownell's Oxfo Blue. Use plain steel wool, and rub that baby for an hour, you get a real deep durable finish. Nice purple highlights.
    Soak it in light weight oil for a day or so. No rust.
    Another thing I did was leave the diameter of the blank as GMRB ships them. Turn it down for a .750 gas block. Leave the forward end at .730. I think it may contribute to accuracy. No stress warping from the gas block back, and it certainly is stiffer. Funny thing, I can tell the difference handling wise compared to the M4 barrel contour.

    Been using GMRB gunsmith blanks for TC Contender barrel's with the same excellent results.

    You guys make great products. It is a joy to spend money on such quality craftsmanship in our economy of corporate and Chinese junk.

    Keep It Up. It is what makes America Great.
    Tell those guys out back turning all the excellent barrels, my Hats Off to them.

    You guys been considering a .50 Cal Ordinance barrel blanks?
    I be a customer. Got a single shot design started in on. Sure rather have a GMRB blank for it.

  3. The Acme In Rifle Barrel Blanks 5 Star Review

    Posted by on 4th May 2019

    Happy Happy Happy! Machined a 9.5 inch barrel from this chambered blank, ended up with an amazing accurate shooting AR15 pistol. Took the time to indicate properly to .0001, for a precise muzzle crown and thread. GMRB did all the hard work. And what is not to like about a high quality chrome lining. I consider this feature to be a pre-requisite for a defense rifle.
    Everything about GMRB work and materials is 1st class from what I can determine and the results speak for themselves.
    It is always a great thing to receive such high quality for my money.
    Be awesome if you guys produced other parts for the AR platform. I think you would be the standard all others would go by.
    This is my 3rd chambered AR blank I've machined. Along with 7 other GMRB barrel blanks. I have nothing else but the highest praise for all the barrels I have produced. Without exception every one has removed inaccuracy from each of the builds due to the barrel. This really makes a profound difference. It is of such exceptional contribution to accuracy I could never think of using another barrel makers barrel blank.
    Next is a long range AR10 using your .308 Chambered Blank.

    If you guys up there in the great state of NH. are thinking of producing .50 cal Ordinance Browning barrel blanks, you have your first customer right here.

  4. Excellent Shooter 5 Star Review

    Posted by on 15th Nov 2018

    I'm so pleased with the accuracy of this chambered blank I had to write a second review on it.
    I'm running it on a minimalist carbine with a full A2 stock, ALG enhanced Mil spec trigger, and troy sights, every part is Mil spec but the Magpul grip and forend. It is as a 80% build.
    It shoots so well it is all I'm interested in using for deer hunting and pest control on my farm. Using Hornady 110grn V-Max Black Ammo, you site it in 3.5 inches high at 100 yards, it hits zero at 200 yards. With 10 rd Pmags, it is a super light weight handling carbine. Simple. Reliable. Rugged.
    We got kill orders from F&G for deer in the cornfields. Filled 10 tags, plus a doe on an early Doe season for land owners. 1 shot 1 kill every time. Hit them in the chest DRT, any angle. It hits like a 44mag rifle at 50 yards, regardless of distance. Great barrel. There is no way I could claim this without the crazy iron sight accuracy of this chambered blank.

    It isn't a fluke, cause I used a .556 chambered blank on another build, same set up but with an Aimpoint Patrol red dot. I've never grouped so tight with a .556 AR.
    The confidence factor is off the charts when you can build a weapon which is so brutally dead nuts on. I'm talking real world real use.
    If you have any question in your mind, chuck it. Get yourself one of these chambered blanks, take your time, get it zeroed on your lathe, have yourself a match grade barrel with military grade chrome lining at a super good price.
    Next is their .308 chambered blank and a dead nuts accurate AR10.

  5. Great Barrel 4 Star Review

    Posted by on 8th Feb 2018

    I only gave the barrel 4 stars because I haven't shot it yet. This is my first barrel from Green Mountain and so far I'm very pleased. This Gunsmith edition was easy to machine and made it easy to build a bolt action ar with no gas system. The price was right and shipping is fairly priced and very fast. The 1-7 twist is great for stabilizing heavier grain bullets. This barrel is a win, win in my opinion.

Showing reviews 1-5 of 6 | Next