Does Bullet Shape Influence Accuracy?

Written by Sierra Bullets Chief Ballistician Tommy Todd

A question we often have to answer here at Sierra is referencing bullet shape and how accurate it is. An example would be the Sierra #2130-30 caliber 150 grain Spitzer bullet and the Sierra #2125-30 caliber 150 grain Spitzer boat tail bullet.

“So which one is more accurate?” is the usual question.

If we did our job correctly in the manufacturing of the two bullets they have equal accuracy potential.  The only real difference between them is the shape of the base of the bullet (flat-base as compared to boat tail). This shape difference does not change the potential of accuracy, but it DOES change how the bullets shoot in individual guns and possibly the load required to deliver optimum accuracy. Sometimes a shooter will do a load workup and hit an accuracy node quickly with one bullet and have good accuracy, but when they switch to a similar bullet they experience a lesser accuracy with a similar load workup session and decide the first bullet “shoots better” in that gun. If both bullets are produced to equal accuracy potential, it is most likely that the load workup missed the combination that would optimize the accuracy of the second bullet and more testing would reveal that accuracy potential. Before I get in hot water with a lot of you shooters, this is not always the case and sometimes guns just WILL NOT shoot the second bullet design despite any load utilized.

I have also had shooters inquire if a bullet with a higher ballistic coefficient (BC) (more efficient shape) is more accurate than one with a lesser BC. This scenario is very similar to the one written above. Despite the bullets being shaped differently if produced the same the accuracy potential is equal even if the efficiency (BC) of the two bullets are different. The shape of the bullets can and does change the load tune (combination of powder charge, distance from ogive to barrel rifling, neck tension etc) and how finicky that a bullet is to changes or variations of the load that makes them shoot to their potential. Again, before I get in trouble with you shooters, please realize that I am referring to sheer accuracy in a NO WIND condition, it goes without saying that the higher BC bullet is usually more desirable in the environmental conditions we have to shoot in.

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10 Responses to Does Bullet Shape Influence Accuracy?

  1. ernest bryson says:

    You know the bullets are reversed, right?

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    • Thanks for letting us know Ernest, we have replaced the image. Sorry for any confusion.

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    • Michael says:

      I shoot a lot of long-range; benchrest, PRS, plinking steel at 1K, etc. But i deer hunt in GA with the 125 Pro Hunter in a 308. Love that bullet. Although i wouldn’t want to shoot it too far due to the low BC, inside 300 it’s basically bang, splat, instant death. Shoots about 1/2″ groups, expands perfectly everytime. Hard to beat

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  2. Steve Tripp says:

    Perhaps a comparative trajectory chart or graph would help people the other differences?

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  3. Jeff Walker says:

    Send Ernie a hat for spotting the error,,Good bullets ,, keep up the good work

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  4. Bob Wolfe says:

    This might be a silly question but… if both are loaded w/ the same amount of powder,primer etc. will the flat base have a higher velocity ?

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    • That will depend upon several factors, the simple answer is, it will IF the pressure as compared to the bullet friction is higher on the flat-base, and if it’s higher on the boat tail then that bullet will have higher velocity. This pressure/friction relationship varies depending upon where you are at in the loading for the bullet/powder in the cartridge you are shooting. USUALLY the boat tail will give slightly higher velocities due to less bearing surface and yet the bullet being longer which takes up more case capacity and produces more pressure. Tommy Todd – Chief Ballistician

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  5. Pingback: Does Bullet Shape Influence Accuracy? | Rifleman III Journal

  6. Eric says:

    Flat bottom (FB) bullets usually have a longer bearing surface than their boat-tailed brothers, so in theory the FB bullets have a greater stabilization in the bore. The question becomes, how much stabilization is enough? Secondly, the supersonic bullets are effected less by drag than when in sub-sonic flight, but the bullet has to go a long way to become sub-sonic. Lastly, the barrel harmonics might not be right for the boat tailed bullet with a higher ballistic coefficient and the FB bullet might shoot better. In other words, barrels don’t behave the same with identically loaded bullets of two different designs.

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  7. Danny East says:

    40 years ago, I came home with a Remy 700 ADL in ’06. 1st stages of learning how to roll my own caused some bedding and free floating to happen, and then some nice work by a gunsmith on the Walker trigger down to 3 lbs. Using several makes and models of bullets, the Sierra #2130 showed the most promise. Kept increasing the OAL and adding more IMR 4350 and stopped at 60 grains. With the best recoil pad at that time period, 3/4″ 5 shots groups were the norm. Finally got a Crony and it was over 3k fps, and could ring a 6″ gong at close to 500 yds. with regularity. Now being on the wrong side of 70, it rarely gets out to the range with that same load. Ouch is the reason why.

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