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  1. #1
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    best twist rate for 300 Blk

    Thinking about building a 16" 300 BLK upper. I figure Ill be using mainly 150 grn ball . Might try hunting with 150 SPs. that being said shoud I go with a 1/7 or a 1/8 twist. thanks

  2. #2
    I have shot everything from 123 gn up to 240 gn and just about everything in between in my 1:8 twist barrel. The 240s seem like they were pushing it a little bit but they were acceptable, just not optimal. On the high end the 208s and the 215s I shot in them seemed to be just fine. On the low end the 123s were exceptional the 150s were just about as good.

  3. #3
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    Quote Originally Posted by Shooter McNasty View Post
    Thinking about building a 16" 300 BLK upper. I figure Ill be using mainly 150 grn ball . Might try hunting with 150 SPs. that being said shoud I go with a 1/7 or a 1/8 twist. thanks
    ACC, who developed the cartridge, recommends 1:7... HOWEVER, if you are not using it as they intended (subsonic loads) the 1:8 is a better choice.

    Keep in mind that the .300 Blackout was not designed as a hunting cartridge. It was designed as a subsonic cartridge to take best advantage of suppressor technology. Not saying it won't kill deer... Just saying that there are better choices for killing deer in an AR platform.

  4. #4
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    thanks guys!!!

  5. #5
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    Quote Originally Posted by Shooter McNasty View Post
    Thinking about building a 16" 300 BLK upper. I figure Ill be using mainly 150 grn ball . Might try hunting with 150 SPs. that being said shoud I go with a 1/7 or a 1/8 twist. thanks
    Using 150 grain bullets then either will work just fine.

    I have some 1/7 & 1/8 twist 300 blk guns (a few of each), if given my choice they would all be 1/7 twist as I get better accuracy in heavier longer (subsonic) bullets with the 1/7 twist. Not a big difference but judged over many 6x5 targets (averaged) shot at 100+ yards then the 1/7's start to show a positive accuracy trend. At 50 yards I really can't tell the difference unless the subs are running on the slow side.

    At 100 yards plus and with longer 220+ grain bullets some are j-u-s-t starting to go unstable at that distance.

    It is a constant struggle to get (and maintain) stellar accuracy with the subsonic 300 black out. Acceptable accuracy = yes, precision accuracy= not guaranteed.

    With super sonic (lighter, shorter bullets) then 1/8 will get you decent accuracy no questions asked. Your limitation on accuracy with either 1/7 or 1/8 will be those 150 grn ball and possibly the brass.

    To me using .223 or 5.56 brass is also an accuracy limiter unless you neck turn as the cut down .223/5.56 brass will have thicker necks as the case is cut in a thicker part of the case. Sizing down to .30 also work hardens the neck. (if I want accuracy from cut down .223/5.56 brass in a 300 blk gun then I neck turn & also anneal before loading)

    As for 1/7 or 1/8 barrels, the problem is in finding 1/7 twist 300 blackout barrels as a number are only offered in 1/8. Personally I won't buy another 1/8 300 blk barrel as I am seeing more 1/7's lately, plus I shoot a LOT of suppressed subsonic.

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