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AR15.COM
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5/29/2010 12:27:00 PM EDT
As per manufacture


           BULLET           -             WEIGHT            -             OAL

          SMK                -                 69              -                   .902
          SMK                 -                77              -                   .978


         Hornady              -              68             -                    .991
         Hornady              -              75              -                   .990


         Nosler               -                 69           -                      .900
         Nosler               -                 77            -                     .980

 Many say that bullet length has more to do with the ability of a barrel to stabilize a bullet than the weight. Many also recomend the 68 gr Hornady in 1 in  9 twist barrels.

If the length of the bullet has more to do with it shouldn't the 77 gr smk or nosler stabilize better than the 68 gr Hornady ?
5/29/2010 1:30:22 PM EDT
[#1]
Quoted:

Many say that bullet length has more to do with the ability of a barrel to stabilize a bullet than the weight. Many also recomend the 68 gr Hornady in 1 in  9 twist barrels.

If the length of the bullet has more to do with it shouldn't the 77 gr smk or nosler stabilize better than the 68 gr Hornady ?


It has more to do with bearing surface or how much surface area of the bullet is in contact with the rifling.  Normally longer bullets have more bearing surface and thus the relationship between length and stabilization.

Check this out

Rob Robideau
Personal Armament Podcast
5/29/2010 1:43:38 PM EDT
[#2]
Not necessarily, Fairchase

The ability of the barrel to stabilize a given bullet is based on the barrel twist rate and the weight of the bullet.
Velocity also plays a role since it is what determines RPM's of the bullet.

Long range stability gets more into aerodymaic forces that are acting on the bullets nose (ogive) to try to overturn it. A bullet with a longer, pointier ogive will be more aerodynamically stable than a bullet with a short blunt ogive. The aerodynamic center of pressure that is trying to tumble the bullet is farther back on the bullet with the long ogive and therefore has less overturning torque apllied to the center of mass.

Recommended Reading
Try This
Thank You Bryan Litz for improving my understanding of ballistics.

5/29/2010 1:44:13 PM EDT
[#3]
Quoted:
It has more to do with bearing surface or how much surface area of the bullet is in contact with the rifling.

Not really.  It's the center of gravity and aerodynamic stability... length is a rough shortcut.
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