6.5-06 1-10 twist with 130 Bergers

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Tinbender, Apr 4, 2015.

  1. Tinbender

    Tinbender Member

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    I have a 6.5-06 with a 1-10 twist barrel. I have had good success with most bullets I've tried, 120 grain match kings and pro hunters shoot very well. Barnes 120 ttsx have been disappointing but I can live with the 100 grain ttsx shooting very fast and around 3/4 inch groups at 100 ( I'm in California so if I want to hunt legally I have to settle) My favorite bullet so far has been the 123 grain Hornady SST which I have had very good results with. I had never shot the Bergers as I've seen my dad try to shoot bergers in different guns at less than the recommended twist rate and they tumbled, basically the bullet would hit sideways at 100 yards. So I always took the recommended twist rate from Berger as gospel.

    My friend, however, has been on me to try the 130 grain hunting vld's in my rifle. I figured they wouldnt spin but ended up buying a 12 pack, loaded up a couple different loads with hybrid 100v and seating the bullets about .005 off the rifling, and low and behold, they shot very well. Well under 1/2 inch and the holes int he target looked perfectly round. Keep in mnd this was only at 100 yards, but seeing that Makes me think that I may be able to dial something in with these.

    So with all the background I can provide, my question basically comes down to, if the bullets seemed to stabilize well, in what I would call perfect shooting conditions, am I chasing fools gold in trying to work something up here that would be consistent, or did I get lucky that they shot like that, and a little wind will start blowing them off and they will become unstable. I love the Bergers, because of the high bc and because of what I've seen them do to animals, but I just don't know if i got lucky and it won't be consistent or if the 1-10 twist can actually handle these bullets. I do have the 123 SSTs to fall back on, which have a listed bc of 510 compared to Berger's 550, but I'm not sure if Hornady my be embellishing a little where I trust what Berger is putting out there.

    So basically, do I keep trying the Berger 130s even though they tell me it won't work, or am I just wasting my time and gremlins will start popping up and I'm better off with the shorter bullets that I know work well?
     
  2. Darkker

    Darkker Well-Known Member

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    The problem with any "gospel", is the superstitious nature and lack of understanding fact.
    Weight is all but completely irrelevant to twist, stabilization is about LENGTH, and RPM.

    MV * 720 / Twist = RPM

    For an idea, to see if you have a prayer at stability, use this:
    JBM - Calculations - Stability

    You can look-up lengths, then add your specifics.
     
  3. elkaholic

    elkaholic Well-Known Member

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    What elevation are you shooting at?
     
  4. Tinbender

    Tinbender Member

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    Thanks, the JBM says I should have been unstable with what I was shooting, but my actual shooting results didn't seem that way. So is this a situation where real world results matter more than the formula, or was it just pure luck that they shot well and it most likely won't do it consistently?
     
  5. Tinbender

    Tinbender Member

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    I'm about 250 feet above sea level.
     
  6. elkaholic

    elkaholic Well-Known Member

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    I am surprised it groups!
     
  7. scottishkat

    scottishkat Well-Known Member

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    John Barsness shot the 140 vld to 700 yards in a 1 in 9 twist 6.5-06. My 25" 1 in 10 6.5-06 shoots 130's without issue I have shot them to 300 no further.

    Good luck and shoot straight

    Bob
     
  8. sundance1972

    sundance1972 Well-Known Member

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    Tagged for interest as I'm waiting for my 6.5-06 barrel to show up in the mail. Just my way of doing things, but once I'm dialed in at 100 and find a promising load, I will try it at 2&300 before I get excited about it.
     
  9. Darkker

    Darkker Well-Known Member

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    Few things to consider, in the answer you seek.
    First is actual twist rate. It is very normal for a mfg to have up to 1/2 faster/slower twist than stated. So the actual twist will affect the reality.
    The second thing is barrel smoothness. This is the bit about voodoo that really can change things. A rough fast twist is almost worse than a smooth slow one.
    Last is "how" unstable is it? Provided you input all the correct variables in the calc, the air changes will help or hurt. If you are just outside stable (Green, yellow, red are the outcomes) then the first two items I said are where you can see the effect. So for an example, with the velocities my group runs; a 9-twisty 223 isn't exactly "ideal" with the 77gr SMK. The reality is only one rifle struggles to get them stable.
    The last bit is about decay. Since my 77gr's are yellow, they don't group amazingly up close. But velocity decay happens very quickly, whereas rotational decay is very slow. So as the bullet slows going down range, it's relative RPM(relative to velocity) will increase; adding dynamic stability to the projectile.