264" 130g scirocco advertised BC

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by remingtonman_25_06, May 5, 2011.

  1. remingtonman_25_06

    remingtonman_25_06 Well-Known Member

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    Was looking over swift sciroccos the other night and came across something that doesn't seem right to me.

    They claim a .571 BC from a 130g .264" bullet, how the hell do they come up with that??? Thats higher then any bullet that I can really think of besides the 140g VLD/AMAX, and its really not to far off of those. Beats the pants off any other 130 and 140 bullet reguardless. How do they gain almost a whole .1 value greater??

    The 129g SST is pretty sleek and slender itself for a lowly .485

    The 130g AB is also advertised at about .488

    Anyone care to share thoughts or experiences with this bullet?? Love to hear it.

    Think I'm going to make me a phone call to Swift tomorrow while I'm at it, pick there brain a bit...
     
  2. craigf

    craigf Well-Known Member

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    The bc's of the 264 seem to run on the high end. Even the black hills gold ammo is advertised at 2750 and a BC of .58 with a 142 grain sierra matchking.
    I would love for someone with a great understanding of this to add more.
     

  3. Nomosendero

    Nomosendero Well-Known Member

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    Keep in mind that the jacket is VERY thick, which allows a very long, streamlined bullet.

    I have talked to Brad at Swift a couple of times, it appears that they are sticking to their guns on the BC of that bullet. He told me that a little jump was better, .030-.050. Brad commented that this was possibly the best bullet they have made to date.

    They have been shooting for the purpose of a new manual & only mentioned RL powders to me, but most 264 shooters get best results with Retumbo.

    I have a new Ruger Number 1 264, I will try them soon.
     
  4. woods

    woods Well-Known Member

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    I'm using the 130 gr Scirrocco II in my 6.5 rem mag (26" Douglas barrel 1 in 8). First Scirrocco I have gotten to shoot good in any rifle. There are a couple of bullets that shoot a little better but this is typical for me

    [​IMG]
    [​IMG]

    Anyway, I have a Zeiss 4.5x14x44 with the RapidZ800 reticle on it. The Zeiss website calculator says that with the .571 BC and a velocity of ~3200 fps then I could just set it on ~14 power. So I took my load at ~3200 fps, zeroed it at 200 yds and then shot it at 300 and 400 yds. The 14 power didn't work out for me. Had to set the power back down to ~12.5 power to bring the POI up to POA.

    That indicates to me that the advertised BC is not correct or the reticle/calculator on the Zeiss is not.

    Only did this once so need to go back and reshoot 200 yds, then 300 yds, 400 yds and 600 yds to verify.
     
  5. BryanLitz

    BryanLitz <b>Official LRH Sponsor</b>

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    I measured a G1 BC of .491 for that bullet. G7 BC is .251.
    book

    It's got a decent ogive design, but a poor (short and steep) boat tail for base drag reduction. Certainly not a design that could possibly produce a .571 average G1 BC. Even at 3000 fps, the G1 BC is just .515, degrading to .453 at 1500 fps.

    A thick jacket for a long bullet...? Sure it makes the bullet longer, but that doesn't mean high BC. Lengthening the nose and tail will reduce drag, but lengthening the bearing surface does nothing for drag so it's irrelevant.

    None of my analysis included group shooting (precision) testing so I can't comment on that. They may be extremely precise, but the BC claim is not accurate.

    -Bryan
     
  6. craigf

    craigf Well-Known Member

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    The .58 BC I referred to earlier is Black hills specs for the 6.5x284 norma with the 142gr matchking. Didn't know if that made any difference. Still seems a bit on the high side.
     
  7. Nomosendero

    Nomosendero Well-Known Member

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    Good info, thanks!! I did not mean that a long bullet Guaranteed a good BC, merely that it increased the odds with all else equal. Thanks for supplying real numbers, may actually be close to the 130 Accubond that is rated at .488 I think. Have you tested that one.
    Looks like the 130 & 140 Berger look even better now.
    Thanks
     
  8. backwoods83

    backwoods83 Well-Known Member

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    Actually Sierra rates there 142smk topping out at .595 on the high side and they do shoot well, but much better in the lands or just off and just under 3000fps in a 6.5x284. A good idea for a vld hunting bullet is a 130 berger vld modified to accept a bronze, polymer, or aluminum tip to get the bc upwards of .57. Bryan knows his shit, if that's the bc he got, I'm sure that's what it is. But the swifts are a decent bonded bullet if you can get them to group well.
     
  9. 1100 Remington Man

    1100 Remington Man Well-Known Member

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    Great information, I always wounder if Swifts BC was correct for there .264 130gr bullet. I have had very good performance with Noslers 120 BT in my .264 Win Mag. It is a Model 70 factory .264 Win Mag with 24 inch barrel but with it I cannot shoot Berger hunting VLD because of the twist rate of my rifle. I know this is a older thread but has great information.