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AR 1:7 & 55gr bullets

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    AR 1:7 & 55gr bullets

    I am just curious as to why must AR15 barrels are 1:7 and most ammo is 55grs. Mine does not shoot a 55gr too well.
    Seems 55gr needs 1:12 or 1:14.
    Any insight?

    #2
    I based my bullet/barrel choices on this graph.
    bullet twist by Tony Pic, on Flickr

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      #3
      Original m16a1 was 1:12, which doesn't do as well with much over 55gr. M16a2 was 1:7. Most ar15 now have faster twists, which theoretically gives you the ability to stabilize any bullet weight. Your gun may not like light bullets. Have you tried different loads?

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        #4
        Yes, I’ve shot heavier loads and seemed to work ok. But the majority of the ammo available is 55s, and most barrels are 1:7. Doesn’t make sense

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          #5
          Originally posted by Deuce16 View Post
          Yes, I’ve shot heavier loads and seemed to work ok. But the majority of the ammo available is 55s, and most barrels are 1:7. Doesn’t make sense


          There’s plenty of ammo choices in 69-77 grain range that work well in a 1:7 barrel. You just won’t find much cheap surplus ammo in 55 grain.

          Is your gun chambered in 223 or 5.56?


          Sent from my iPhone using Tapatalk Pro

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            #6
            not all AR's have 16" barrels....or 20" barrels. So you need to consider barrel length as well as twist.

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              #7
              I have a 16” barrel with 1:7, and it’s doesn’t even shoot 62s well. So I guess I’ll swap the barrel out to 223 Wylde with 1:9 or 1:10
              I want it to shoot good, outside of an MOA isn’t good to me.

              Comment


                #8
                Mines a 1:8 wylde and will shoot 40gr-62gr factory loads under an 1”. I’ve never shot 5.56

                The “chart” is garbage from all I’ve seen... but might be spot on with hand loaded ammo


                Could be your barrel... or gun. Most AR are “budget builds” and do good with “minute of beer can”.

                Factory 42 pound 20 grit mil spec trigger? Bulk/plink ammo? Bipod or bag?

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                  #9
                  Originally posted by Deuce16 View Post
                  I have a 16” barrel with 1:7, and it’s doesn’t even shoot 62s well. So I guess I’ll swap the barrel out to 223 Wylde with 1:9 or 1:10
                  I want it to shoot good, outside of an MOA isn’t good to me.


                  My kids AR was the same way.
                  Got some 67s and it tightened up a lot


                  Sent from my iPhone using Tapatalk

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                    #10
                    Originally posted by Deuce16 View Post
                    I have a 16” barrel with 1:7, and it’s doesn’t even shoot 62s well. So I guess I’ll swap the barrel out to 223 Wylde with 1:9 or 1:10
                    I want it to shoot good, outside of an MOA isn’t good to me.
                    If you’re looking to shoot MOA with cheap 55 gr you’re not going to be happy with any barrel. Pony up for higher quality ammo, which most is in the 68-77 range. That 7 twist will shoot those just fine if it’s a decent barrel. 1-8 is an ideal twist for an AR. Mag length restrictions takes away any advantage of anything over 77 grs, and an 8 twist will do just fine with the 77s down to 55s. Below that it’ll shoot ok, but not great. Most ARs aren’t MOA guns on their best day, and most mass produced 223/556 isn’t either. Shoot quality ammo through a quality barrel, and use the right weight range for your barrel.

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                      #11
                      Long range shooting is the current fad, so manufacturers are making barrels to stabilize heavy bullets.

                      I’d be just fine with a 9 twist for 90% of my shooting.

                      Comment


                        #12
                        Originally posted by TacticalCowboy View Post
                        Long range shooting is the current fad, so manufacturers are making barrels to stabilize heavy bullets.

                        I’d be just fine with a 9 twist for 90% of my shooting.
                        What bullet would you shoot out of that 9 twist? I have a 1:9 16” bull barrel I spent a good bit of money on and can’t get it to group well.

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                          #13
                          I have a 7 twist and it loves 55 gr flat base bullets and shoots 69 gr like crap!

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                            #14
                            Originally posted by Deuce16 View Post
                            Yes, I’ve shot heavier loads and seemed to work ok. But the majority of the ammo available is 55s, and most barrels are 1:7. Doesn’t make sense
                            My one 5.56 AR, has a 1 in 9" twist. I have only seen 1 in 9" and 1 in 8" twist on 5.56" ARs, in recent years. I never paid any attention to the Colt ARs we had years ago.

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                              #15
                              Originally posted by Cantcatch5 View Post
                              What bullet would you shoot out of that 9 twist? I have a 1:9 16” bull barrel I spent a good bit of money on and can’t get it to group well.
                              Try a Speer 52 gr. hollow point. I spent a lot of time working on hand loads for my 5.56 AR. These made a big difference in accuracy with my gun. Load them as long as you can and still fit in the mag. My gun went from 1 1/2" groups to 1/4" groups. I tried a quite a few different 55 gr. bullets, then realized the reason my gun was producing such pour accuracy. The bullets were a long ways from contacting the rifling lands, when loaded to a length that would fit in the mag. These bullets mostly fixed the problem, because of the flat nose and the different shaped ogive of the bullet.
                              Last edited by RifleBowPistol; 08-16-2020, 02:52 PM.

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