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GM-B5 Gunsmith Edition 300 Blackout Unfinished Barrel

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Product Description


17" Gunsmith edition blank,  Chrome lined bore and chamber with a phoshate extension.  Made with 41V50 steel, 300 Blackout cal, 1:7" twist. 3 lbs.

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Product Reviews

  1. GMRB Quality 5 Star Review

    Posted by on 8th May 2017

    Like all the barrel blanks from Green Mountain I have used, this 300AAC AR-15 chambered blank is 1st rate in every respect. Plus you get an excellent price that leaves you with room to make a decent penny and offer it at a reasonable price.
    Not to mention the excellent customer service, and shipping.
    Win-Win all around.
    You all should be proud at GMRB, you guys have a great thing going.

    As a gunsmith machinist, I find these blanks are easy turning and consistent results are achieved, and because of that it is simple to achieve .0005 or less runout on chambering, crowning, and threading. And that is key to the level of accuracy I am achieving using GM barrel blanks.
    This particular product though, is on the next level. You are able to produce any number of configurations easily and not have to go through the time and process of a mil spec chrome lining job.
    And these are 1-7 twist blanks, which is perfect for stabilizing the 200+ grain subsonic rounds.
    Top shelf all the way.