Announcement

Collapse
No announcement yet.

twist rates

Collapse
This is a sticky topic.
X
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Well for those of us that prefer a simple yet detailed explanation, this article by Dan Lilja, http://www.riflebarrels.com/faq_lilja_rifl...m#twist%20rates I think explains it pretty well. The one thing to keep in mind is it is not the weight but the length which can explain the exceptions.
    Just trying to keep the world safe from Coyotes, Bobcats and dope fiends.

    Comment


    • #17
      HI Bluedeacon,

      Thanks for the link.

      Yes, I agree on the bullet length issue (e.g. Scenars are VLD bullets), but still wonder about the meaning of the velocity and BC. I.e. the influence of the bullet's length, velocity and BC (BC comes from bullet's form factor (shape) and sectional density) alltogether could cause the exceptions. Just reasoning, may not be true, but it does sound logical and rational, doesn't it.

      Like I said, I'm just trying to find the logic and rationality behind these exceptions.

      Shoot well !

      Cheers,

      Mace

      Comment


      • #18
        Check out Black Hills' website... they have some good info on the best twist rates for the bullet you're shooting.
        http://www.black-hills.com/factoryNewR.htm

        Comment


        • #19
          One thing I have seen change from my post back in 2005. When I shot matches years ago we would use the 190 grains SMK in hard wind conditions. Now after shooting the 175 grains SMK's for 15 years the difference between the 190 and the 175 at 1000 yds it's enough to warrant the change.

          Thus, my taste have changed. My 308's from now on will be 1 in 12 twists. I don't see myself shooting anything other than the 175 SMK. With that the RPM I need to reach is done easier with the 1 in 12 twist without as much spin drift at 1000 yds.

          While the 1 in 10 reaches the RPM I want faster, at long range it begins to slow down faster as well. The 1 in 12 gets the RPM a little slower but than maintains it at longer ranges.

          Over the years I've tried to stay away from dedicating a rifle to one bullet. Sierra designed the 175 SMK just for the 308 win. and I believe it's about as good as it gets. I've shot in tons of matches against the 155's and other bullets and still came out on top with the 175. In hard wind conditions it hold up as good as anything I've thrown down range.

          Just my opinion.

          Take care, flea
          "with the patience of an oyster....I watch and wait"

          Training the US, one shooter at a time.






          http://www.centralvirginiatactical.com

          Comment


          • #20
            [quote]
            Here's a pretty good article at the Lilja barrels website on bullet stability as related to twist rate and atmospheric conditions:

            http://www.riflebarrels.com/articles/bulle...fling_twist.htm

            Seems a stability factor of 1.3 is the minimum recommended. Given that, it looks to me like the 11.25 twist is just barely good enough for a 175gr bullet.

            Savages have a twist of 1:10. Guess what Remmys have? 1:12. Yet another reason to buy a Savage!

            Cheers
            --Hawk[/b]
            Hey Hawk, is that twist rate for ALL Rem actions? Model 700's? and heres a stupid question but barrel lenght (true barrel length) is determined how? Stamped into barrel or other? From breech or bullet?

            Comment


            • #21
              Remington 700's have different twist rates depending on caliber and other specs. Their .308's are either 1:10", 1:11.25" or 1:12".

              If you need to figure out the twist rate for your particular barrel, you'll need a good cleaning rod with a swivelling handle and a tightly fitting bore brush. Run the brush into the bore until it fully engages the rifling. Make a mark on the rod that lines up with a mark on the handle (some rods have these marks already). Mark the rod right where it enters the rear of the receiver (blue masking tape works good for this, or a Sharpie marker). Slowly push the rod into the barrel until the rod makes a complete revolution. Once again, mark the rod right where it enters the rear of the receiver. Pull the rod out and measure between the 2 marks. That distance is your twist rate.
              www.precision-applications.com

              It's knowing that when I get up in the morning and my feet hit the floor, the Devil says, "Shit! He's awake!"

              Shortly before World War I, the German Kaiser was the guest of the Swiss government to observe military maneuvers. The Kaiser asked a Swiss militiaman: "You are 500,000 and you shoot well, but if we attack with 1,000,000 men what will you do?" The soldier replied: "We will shoot twice and go home."

              "There are so many Russians, and our country so small, where will we find room to bury them all?" - anonymous Finnish soldier

              Comment


              • #22
                [quote]
                Remington 700's have different twist rates depending on caliber and other specs. Their .308's are either 1:10", 1:11.25" or 1:12".

                If you need to figure out the twist rate for your particular barrel, you'll need a good cleaning rod with a swivelling handle and a tightly fitting bore brush. Run the brush into the bore until it fully engages the rifling. Make a mark on the rod that lines up with a mark on the handle (some rods have these marks already). Mark the rod right where it enters the rear of the receiver (blue masking tape works good for this, or a Sharpie marker). Slowly push the rod into the barrel until the rod makes a complete revolution. Once again, mark the rod right where it enters the rear of the receiver. Pull the rod out and measure between the 2 marks. That distance is your twist rate.[/b]
                Got it. 1:11.25 which is funny because the advertised rate for this weapon is 1:12 so either its correct there or with my measurement. Done 4 times just to confirm. I also figured out a 24" barrel. Im still gonna run those three different bullets and see what she does with each and settle on an all around for shooting/hunting and one for distance. Thanks

                Comment


                • #23
                  In my .30 magnums I prefer to run a 1:10" twist to better stabilize the heavier bullets. For a .308, anything from 1:12" to a 1:10" works fine with a 168 - 175grn bullet.
                  www.precision-applications.com

                  It's knowing that when I get up in the morning and my feet hit the floor, the Devil says, "Shit! He's awake!"

                  Shortly before World War I, the German Kaiser was the guest of the Swiss government to observe military maneuvers. The Kaiser asked a Swiss militiaman: "You are 500,000 and you shoot well, but if we attack with 1,000,000 men what will you do?" The soldier replied: "We will shoot twice and go home."

                  "There are so many Russians, and our country so small, where will we find room to bury them all?" - anonymous Finnish soldier

                  Comment


                  • #24
                    [quote]
                    Hi,

                    I know this is an old topic and much discussed issue, but nevertheless a few comments.

                    Very good and informative hands on experiences from all the Gents above.

                    And yes, we all know the so called main rules of determing a twist rate. But as Flea pretty much summarized it all, the best bet for heavy bullets is 1:10 rate and for lighter bullets 1:12 rate; and 1:11 rate falls in btw these two as a compromise.

                    However, there are so many interesting exceptions to the rule like M700 referred - well pointed out M700; really hard to argue with success - I agree.

                    Furthermore, Thomas W Bruner also pointed well out that 1:12 rate works fine with heavy bullets in M40 series rifles.

                    I'm really interested in finding reasons for these exceptions, since I have similar practical experiences from the field during past yrs. There has to be a logical and rational reason for the exceptions. What it is, I don't know, but I try to figure it out.

                    A recent field example: Shooting 155 gr Scenars 1:10 twist rate worked perfectly well from short barreled 20" semiauto and bolt rifles in .308 caliber at 1000 meters. Also 1:11 twist rate worked similar ways, but not 1:12 rate. Why so? 1:12 twist rate semis and bolt guns were GTG up to 900 meters (20" barrel) and as said already 1:10 & 1:11 semis and bolt guns were GTG up to 1000 meters (20 "barrel).

                    I would say that light bullets (let's say 145 - 155 gr) overstabilze when shooting from a 20" barrel with 1:10 twist rate and at the extreme max. distance let's say 1000 meters (the distance where one can still engage and hit targets and the bullet is still supersonic and stabilized > round bullet holes in the target), the bullets are still stabilized due the higher start spinning rate and thus enable bullets to score, while still being supersonic - this was of course simplified example.

                    Wheathers light bullets (145 - 155 gr) are pretty much stabilized already all the way when shooting from a 20" barrel with 1:12 twist rate and at the extreme max. distance 1000 meters aren't any more stabilized due to the slower start spinning rate and thus aren't able to produce score - they are still supersonic though.

                    Twist rate 1:11 is a compromise btw these two above twist rates and seems to work alright at least so far.

                    With longer barrels, over 20", light bullets (145 - 155 gr) seem to stabilize well regardless of twist rate. Therefore, taken the above example, all twist rates 1:10, 1:11 and 1:12 are GTG at 1000 meters; bullets are stabilized (round bullet holes) and naturally supersonic.

                    Why is that? Is it due to extra velocity gained from longer barrel? Quite likely maybe, hard to say.

                    Nevertheless, an interesting issue, not trying to reinvent the wheel, just merely find the logic and rationality behind these exceptions.

                    Just my two cents.

                    Shoot well !

                    Cheers,

                    Mace[/b]
                    Mace, I am currently putting this puzzle together for my .300 weatherby mag. Its has the 1:12 twist and a 24" barrel. I want to shoot bullets like the Berger 230gr OTM tactical hybrid, the 208gr A-MAX or 190VLD Berger or Sierra matchKings. I may try to go out to 1500yds but mostly in the 300 - 1000+ yd range. I will be using Hornady and Berger manuals for baselines on powder charge etc. Whatchoo think?

                    Comment


                    • #25
                      [quote]
                      Mace, I am currently putting this puzzle together for my .300 weatherby mag. Its has the 1:12 twist and a 24" barrel. I want to shoot bullets like the Berger 230gr OTM tactical hybrid, the 208gr A-MAX or 190VLD Berger or Sierra matchKings. I may try to go out to 1500yds but mostly in the 300 - 1000+ yd range. I will be using Hornady and Berger manuals for baselines on powder charge etc. Whatchoo think?[/b]
                      Personal Info
                      Mace
                      PFC
                      Age Unknown
                      Male
                      Location Unknown
                      Birthday Unknown
                      Interests
                      No Information
                      Other Information
                      Rifle: JJ .338 LM
                      Optics: S B PM II
                      Ammo: 16,2 Scenar .338LM
                      Statistics
                      Joined: 6-November 2003
                      Profile Views: 28*
                      Last Seen: 5th January 2011 - 6:40

                      Mace hasn't been back in a couple of years. The post you quoted was from 2006.

                      He probably got promoted to Sr. Target Holder.

                      Comment


                      • #26
                        [quote]
                        <div class='quotemain'>Mace, I am currently putting this puzzle together for my .300 weatherby mag. Its has the 1:12 twist and a 24" barrel. I want to shoot bullets like the Berger 230gr OTM tactical hybrid, the 208gr A-MAX or 190VLD Berger or Sierra matchKings. I may try to go out to 1500yds but mostly in the 300 - 1000+ yd range. I will be using Hornady and Berger manuals for baselines on powder charge etc. Whatchoo think?[/b]
                        Personal Info
                        Mace
                        PFC
                        Age Unknown
                        Male
                        Location Unknown
                        Birthday Unknown
                        Interests
                        No Information
                        Other Information
                        Rifle: JJ .338 LM
                        Optics: S B PM II
                        Ammo: 16,2 Scenar .338LM
                        Statistics
                        Joined: 6-November 2003
                        Profile Views: 28*
                        Last Seen: 5th January 2011 - 6:40

                        Mace hasn't been back in a couple of years. The post you quoted was from 2006.

                        He probably got promoted to Sr. Target Holder.
                        [/b]
                        hahahaha I should pay more attention! DUH

                        Comment

                        Working...
                        X