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Practically Shooting

Accuracy difference between flat tail & boat tail?


wwillson

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In my old benchrest days, all my target loads for the .22 & 6mm PPC were flatbase bullets. However, I never shot a match that was longer than 200yds so I never really had the reason to make boattails work to take advantage of the better BC.

When I was working up a load for my 22-250 improved, I couldn't get the Sierra 52gr HPBT match bullet to work very well, but the Sierra 53gr HP flatbase match bullets worked great. I think the real difference between the two bullets had more to do with the slow twist barrel I was using(1-14) than the bullets thenselves.

If you look at some of the calculations for barrel twist vs bullet length and velocity, you will find that the longer boattail bullets really require a quicker twist to take advantage of the better BC they offer.

The new lead free bullets that are now being made are really long for a given weight. Twist rates of barrels will be really critical to stabilize these long bullets for good accuracy.

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Brushing the cobwebs from alcohol soaked brain cells,,, the boattail is supposed to retain stability when bullet comes back below speed of sound. Supposidly, there is turbulence created when breaking the speed of sound both speeding up and slowing down. Bullets break SOS speeding up before they ever leave the bbl, but as they slow back down it's supposed to cause yaw and weave, keyholing, etc.

Now, who's gonna shoot em far enough that they're going to be back that slow?

Bob

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