speed v's accuracy

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  • speed v's accuracy

    Ok guys, I'm torn between two loads in my 308 omark. The problem I've got is the most accurate load I've shot with this rifle is only 44.3grn @ 2825fps compared to 46.6grn @ 2915 fps. I've been told that 2825fps isn't fast enough for the longer ranges. But it groups a lot better than the faster load. Does the 90 fps difference between the two loads mean that much of a difference at the paper end of things?

  • #2
    I'd always go with the more accurate load as long as its still supersonic out to the range you want to shoot. I also learned that the lower accuracy nodes tend to be more consistent over a range of conditions than the higher accuracy nodes

    the only time you would really worry about getting a higher launch speed (within reason) is to get reasonable expansion on game at longer ranges

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    • Guest's Avatar
      Guest commented
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      What increments have you tested and have you adjusted seating depth yet?

    • Guest's Avatar
      Guest commented
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      I would always choose the accurate option. As the great Townsend Whelen tells us "the only interesting rifle is an accurate rifle", you are still screaming along at 2900fps and lower accuracy nodes use less powder, slightly less throat erosion and slightly less noise and recoil. My most accurate .243 load is only . 5grain off the minima however I know where it is going to hit every time - far preferable to the highest possible velocity with a scattergun effect.

      Originally posted by nuthead" post=17064
      the only time you would really worry about getting a higher launch speed (within reason) is to get reasonable expansion on game at longer ranges
      Sometimes there can be too much velocity and as a result early fragmentation and lose of penetration. Have a look at the Woodleigh bullet website and a lot of their suggested velocities are down fairly slow compared to target work such as starting around 1900fps for .308 as an example:
      http://www.woodleighbullets.com.au/images/stories/downloads/woodleigh_bullets_catalogue_2013.pdf

  • #3
    Sorry guys, I should have mentioned that I'm talking about target shooting not game shooting.
    Can anyone tell me at what distance is my projectile still supersonic with a muzzle velocity of 2825fps. I'm using 155.5grn berger full bore target projectiles with a bc of .464 . 44.3grn of ar2208 powder out of a 26" barrel with a 1:12 twist.

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    • Guest's Avatar
      Guest commented
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      you'd be supersonic to roughly 1100m

    • findingtime
      findingtime commented
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      1280 yards approx or 1170 m so you'll just make it .... an extra 90 fps would mean 1350 yards or 1234m

    • Guest's Avatar
      Guest commented
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      Originally posted by scottmatt" post=17080
      Sorry guys, I should have mentioned that I'm talking about target shooting not game shooting.
      Can anyone tell me at what distance is my projectile still supersonic with a muzzle velocity of 2825fps. I'm using 155.5grn berger full bore target projectiles with a bc of .464 . 44.3grn of ar2208 powder out of a 26" barrel with a 1:9 twist.
      Have a real close look at this link and spend the time to get all the data input correct. When it does the calculations you can record the different "Zero" points if you do them and / or print them out for future use.

      One of the best and most accurate Trajectory / Ballistics Calculators going around. Check out the rest of the site.

      JBM Ballistics .......

      http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

  • #4
    Cool. Thank you on the way

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    • #5
      Andybangflop I've done a bit of load development for this rifle.
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      Then I tested between 44.0 & 44.9
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      Then I was told that my loads weren't fast enough so I went to 46.4grn from the first round of testing
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      Then after some more testing I tried 46.6grn
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      • findingtime
        findingtime commented
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        Bit of work in that... Have you mucked around with seating depth ??? Where are you atm in relation to the lands ?

    • #6
      Thank you. They are pretty cool.

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      • #7
        "Fast is fine, but accuracy is everything"

        Wyatt Earp
        "For it is the doom of men that they forget"

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        • #8
          Always choose accuracy IMO

          My Fclass load is mild for the cartridge and I could squeeze much more MV out of her.
          The problem is when load testing the hot loads they shot well except for the odd flyers.
          I worked and worked at the hot load and nothing fixed the odd loose shot.

          I reduced my load by 1gn and walla! Tight groups consistently.

          In the Fclass game you dont have many shots to create a good score. Why run a load that may potentially could cause a flyer resulting in a bad score.

          As for FPS and chronograph testing.
          I have pretty much removed that from my load development. I think the proof is in the pudding and if the load groups well at 100 and at longer ranges shows no signs of vertical you are good to go.

          If I dont know my MV I dont need to worry that I could squeeze more out of it.
          At the end of the day we are both new to the game and super accurate rifles and super fast MV will not improve our scores as much as experience at reading those bloody flags.


          JH

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          • BlueBikesBlackGuns
            BlueBikesBlackGuns commented
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            at 2825fps a 155grn Berger VLD you will still be supersonic out past 1000yards.

          • Guest's Avatar
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            Originally posted by John23" post=17191
            Always choose accuracy IMO

            My Fclass load is mild for the cartridge and I could squeeze much more MV out of her.
            The problem is when load testing the hot loads they shot well except for the odd flyers.
            I worked and worked at the hot load and nothing fixed the odd loose shot.

            I reduced my load by 1gn and walla! Tight groups consistently.

            In the Fclass game you dont have many shots to create a good score. Why run a load that may potentially could cause a flyer resulting in a bad score.

            As for FPS and chronograph testing.
            I have pretty much removed that from my load development. I think the proof is in the pudding and if the load groups well at 100 and at longer ranges shows no signs of vertical you are good to go.

            If I dont know my MV I dont need to worry that I could squeeze more out of it.
            At the end of the day we are both new to the game and super accurate rifles and super fast MV will not improve our scores as much as experience at reading those bloody flags.


            JH
            Good call.

        • #9
          Originally posted by scottmatt" post=17059
          The problem I've got is the most accurate load I've shot with this rifle is only 44.3grn @ 2825fps compared to 46.6grn @ 2915 fps.
          Accuracy 1st as others have said.

          Going from your two loads, have you tested to & maybe just above max load?

          Looking at your figures I would say that 46.6gr load is not on the node.

          The nodes in my 308 tend to be around 150fps appart, of course different barrel harmonics with different rifles may change this but I'm still suprised that youré nodes could be within 90fps of each other.
          Maybe you have another "true node" just over 47gr. (Disclaimer - pls don't try it unless you are confident & cautious of pressure signs)

          Oh,
          Another thing I found with my 308 loads.
          The 155gr pills shot better with AR2206H
          Again, may not be relevant with a different rifle but worth a thought.

          Mick.

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          • Guest's Avatar
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            Have you tested the bergers jammed into the lands? 0.00" or -0.001"

          • Guest's Avatar
            Guest commented
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            As you have said, I'd be testing both loads at a longer distance than 100mtrs to see the difference!
            I prefer milder more accurate loads myself, they are easier on the brass to!

        • #10
          Ok I've changed my loads this morning back to 44.3grn of 2208. I'll see how they go today at 500yrd. They were the best loads through all my development at 100m so I hope they hold together out at 500yrd and beyond. Will let you guys know how they go.
          And if they go to shit I've got someone else to blame :P . Thanks for your posts.

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          • #11
            Well, the only good thing that came out of today's shoot was I got to spend the afternoon with a good bunch of people. The wind was up and switching and the light loads copped a bashing. What shot really well at 100m was terrible at 500yrd. They were all over the place in the wind. But at least I got them out of my head and I now have a lot better shooting position thanks to John23. Thanks again John it is a lot more comfortable than the position I was shooting in. I'm going back to the 46.6grn for the prize shoot next week end.

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            • BlueBikesBlackGuns
              BlueBikesBlackGuns commented
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              Originally posted by scottmatt" post=17459
              The wind was up and switching and the light loads copped a bashing. What shot really well at 100m was terrible at 500yrd. They were all over the place in the wind.
              Hi Scottmatt,

              Did you keep a plot sheet? (to record where the rounds fell). Id tell you to forget the horizontal and look only at the vertical. If you held a consistent vertical group then that is a win.

              Reading wind is a skill that takes time to learn (or a good wind coach) If your error was only in the horizontal plane then don't blame the loads. Just need more practice at reading wind. At the velocity you are talking at 500y the Berger VLD would be deflected by as little as 1/4 MOA in 20mph wind.

          • #12
            I would not be blaming light loads for not shooting well in a breeze.

            It is well known that milder loads produce the best accuracy and are more consistant under varing conditions. Hot / hotter loads tend to be inconsistant when conditions like temperature changes even with our temperature stable ADI powders.

            How well can you read the wind, how well can you adapt to that change of conditions is the question I would think about.

            I take my thoughts from some advice I was given by my mentors, state, national and international top class shooters, past and present. Like last weekend at Batemans Bay when winds came up to 50kph those that had the experience showed against those that lacked but were they hot loads.....no

            I think it was Stuart Elliott that said to me once that one reason the USA lost the Benchrest Championship was they chose to use the higher end of the load data rather than the more consistant lower end mark..... we'll see what happens at Silverdale soon.

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            • Guest's Avatar
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              Originally posted by Mega" post=17476
              I would not be blaming light loads for not shooting well in a breeze.
              .
              I fully agree with that statement in mild or consistent conditions. Think of the wind at NARC like the bubbles in a spa bath.
              Not 2 flags point in the same direction and at times flags at the same distance run in opposite directions.
              Its a bloody mess and a real baptism of fire learning there. IMO this is a range where ballisticly superior cartridges will out perform the perhaps more mild.
              I will also mention in regards to that last statement is that experience conkers all.


              After watching Scottymatts first 2 shots landing extremely low on the target due to the light load I have to agree that he would have been better with some more MV.
              What put it in perspective for me was.

              500m target

              I dialed 7.25moa using a light load in the 6.5x47
              Scott dials 8.?moa using his hot load.
              Yesterday Scott dialed 12.?moa !!!

              The long flight time and lower BC 308 pills were definitely a disadvantage for Scott.
              Scott shot a near perfect vertical and only dropped points to the wind.

              I know if one of the pro's picked up Scotts rifle they could have shot perfect scores given the condition. And I know thats what the Fclass game is all about.
              But Scott is new to Fclass (like myself) and until you learn to read those big old slow flags points will be dropped to lack of experience.

              I guess my point being if Scotts pills were coming out 100fps faster the 5's may have been 6's and so on.

              Much like the Fopen that I was shooting. If I was running 6.5x284 or 7SAUM like the rich boys I would have bucked the wind better and held better scores.

              My original post in the thread was on the lines of accuracy beats MV period.
              Yesterday changed my mind on this topic a little.


              JH

          • #13
            If it was just windage that was the problem l wouldn't have had such a bad thought of the load. There is about 3.5moa difference between the two loads of 44.3 and 46.6 that i shot at the same distance last week. There was also about 1.5 - 2moa in elavation in the groups shot.

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              Originally posted by scottmatt" post=17535
              If it was just windage that was the problem l wouldn't have had such a bad thought of the load. There is about 3.5moa difference between the two loads of 44.3 and 46.6 that i shot at the same distance last week. There was also about 1.5 - 2moa in elavation in the groups shot.
              Are you saying 3.5MOA difference in " Group " size or in the difference of where the groups are....???

              I would suggest that you change your load development distance to at least 200m to get some better and true figures...In my view 100m is too close for developing long distance loads.

          • #14
            I'm using 44.3 of 2208 as well but with the 155grn Nosler CC... I took accuracy over speed even though I get some head scratching and looks from other club members at times.

            Having a good run at 500yds.. I added 1/2 of wind mid string as things picked up to get back in the middle... super happy considering it was off a versapod bipod not a fancy rest, just wish I could do it more often

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            • #15
              Yeah the head wind was a factor for me also.
              It was 0.75moa for me using the 6.5mm.

              JH

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