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Bearing surface length?

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  #1  
Unread 12-23-2009, 03:07 PM
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Bearing surface length?

What would be the results of having a short bearing surface on one bullet versus another? In this case, 7mm Rem Mag with Berger 140 gr VLD (bearing surface of only .122") versus Nosler 140 gr Accubond (don't know what the bearing surface is, but HAS to be a bit more than the Berger). Unless there is a typo on the Berger Tech Data list, that seems to be a really short bearing surface.

Just for reference, the bearing surface of a 168 VLD is .462".
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  •   #2  
    Unread 12-23-2009, 03:53 PM
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    Re: Bearing surface length?

    [QUOTE=txsendero;341582]What would be the results of having a short bearing surface on one bullet versus another? In this case, 7mm Rem Mag with Berger 140 gr VLD (bearing surface of only .122") versus Nosler 140 gr Accubond (don't know what the bearing surface is, but HAS to be a bit more than the Berger). Unless there is a typo on the Berger Tech Data list, that seems to be a really short bearing surface.

    0.122 inch would be a very short bearing surface for a 7mm bullet. But Berger doesn't make a 140 grain 7mm VLD, at least their website doesn't show one. I believe they only make 168 and 180 grain 7mm VLDs and those certainly have longer bearing surfaces. Berger does make a 6.5 mm 140 VLD but it has a longer bearing surface too.

    I'd suggest you check your source again. Sometimes browsers can scramble pdf files. As to what a short bearing surface could do, it would be to possibly allow the bullet to tip in the bore causing large yaw exiting the muzzle and poor accuracy. The bullet might still stabilize at some distance but muzzle yaw introduces an initial angular offset. That doesn't sound like any Berger bullets I've shot which includes most (all?) of their .264, 284, and .308s.

    Last edited by LouBoyd; 12-23-2009 at 04:04 PM.
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      #3  
    Unread 12-23-2009, 04:05 PM
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    Re: Bearing surface length?

    Thanks Lou. The Berger website does show the 140 VLD in 7mm, its listed under the "Hunting" VLD bullets. The chart I looked at looked to be a scanned copy of their Tech Data List on this forum under Barrels Bullets and Ballistics, and it is also on Berger's website as Quick Reference Chart.
    It has got to be a "typo", but I sent a PM to Eric Stecker to see what he says about it, just haven't heard back from him yet.

    Last edited by txsendero; 12-23-2009 at 04:25 PM.
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      #4  
    Unread 12-23-2009, 06:58 PM
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    Re: Bearing surface length?

    I shoot the 140 Berger and Accubond in a 270 WSM with the same load, same distance from lands, and the Berger runs 50FPS less than the Accubond, I contribute this to the bearing surface causing more drag thus more pressure with the longer Accubond.
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