Home Forums Hunting & Shooting Ask The Gunwriters Flat Base vs. Boat Tail - is one more accurate?

Read something interesting lately about flat base bullets being more accurate at short (~400 yds) ranges than boat tail bullets. It had to do with the bullet exiting the muzzle and the flat base having a better chance of pressure being equal around the bullet where the boat tail is still in the barrel when the gas escapes around the boat tail giving the chance to upset the bullet. Any experience with this?

I think the standard answer is that boat tail bullets take longer to stabilize (>200yds), but have better ballistic coefficient. Flat base stabilize quickly (<100yds), but not as good ballistic coefficient.

answer: Flat base are generally more accurate at sub 300yd. Boatails are generally more accurate at greater than 400yd

...YMMV

Mule deer has done his usual thorough study, as have I on a less spectacular scale. He will hopefully comment but my experience is that "It all depends." The .30 cal Sierra FB 150 gr bullet is as as good (accurate and deadly)as any I have ever fired out to 400 yards but the Sierra HPBT will reach a little further and opens up better at longer range.

Terry

The one that is more accurate.

Some rifles simply do not like BT's. Those that do, shoot them more accurately than flat bases so Steelie is correct.

I have found several Weatherby chamberings shoot more accurately with flat based bullets remembering that all Weatherby's do not have freebore.
John

Generally flat base bullets shoot a little better though its not a solid rule. I had an /06 that shot the sierra 180 gr flat base into about 6" at 100 yds while it shot the Nosler 180 gr ballistic tip under and inch.

The same Sierra 180 that I tried in my /06 would shoot 1/2" groups out of a 300 win mag.

Shod

This.

centershot,

Yes, "short range" benchrest shooters have found flat-base bullets are more accurate, the reason they're almost universally used in typical benchrest matches. But the difference isn't enough to show up in most hunting rifles, which have far looser internal chamber and barrel dimensions than benchrest rifles. (This is also probably why some hunting rifles won't shooting boattailed bullets very well.)

However, at longer ranges accuracy depends as much on a bullet's wind resistance as a rifle's ability to shoot tiny groups at 100 or 200 yards. This is why long-range shooters universally use boattails: Everything else being equal, they resist wind-drift more than flat-base bullets.

In the last few years boattails have started to show a presence in the winners circle in Short Range Benchrest. Which is most accurate, either can be, its a combination of a lot of factors, bullet shape being only one that determines which is most accurate in a particular firearm.

I usually find boat tails more accurate.

I guessed its because my sloppy handloading isn't shown up as much with boat tails because they allow me to seat bullets straighter.

But I really dunno.

My most accurate bullet is a flat base, but there are boat tails very close to it, and some flat based bullets are worse than many boat tails. I wouldn't make a bullet decision based on that feature, just not enough of a discriminator in my experience.

prm,

Of course, some flat-based bullets are inaccurate, whether because they're poorly balanced or whatever. But that wasn't the question.

The theory behind flat-based bullets being somewhat more accurate is the square base of the bullet leaves a correctly-made crown more "cleanly" than a tapered boattail. This is why some bullets have very short, steep boattails, or "rebated" boattails, with a sharp, steep angle between the shank of the bullet and the boattail itself. Neither a short, steep boattail or a rebated boattail increases ballistic coefficient as much as a very long, gently angled boattail, but they still increase BC somewhat over a flat-based bullet of the same weight, diameter and ogive shape.

Whether any bullets shoots better in one particular rifle also depends on throat and crown conformation, and probably actual bore diameter as well. Boattail bullets don't seal the bore as well as flat-based bullets (there are also some other factors that go into this, such as jacket thickness and core hardness), and that's also a factor in whether a particular rifle "likes" a certain bullet.

Certainly base-shape also affects how straight bullets are seated in the case neck. Probably the overall trend favors boattails, but I have seen it work both ways in certain cartridges, probably due to other factors, such as the seating stem of the die, whether or not the seating die has a short cylindrical section to keep bullets straight, and even how the case mouth was chamfered.

But in general, yes, flat bases allow bullets to leave the muzzle more consistently than boattails. Whether or not this results in overall finer accuracy at different ranges in any particular rifle is dependent on a host of other factors, and whether or not any individual rifle shoots boattails more accurately than flat-bases doesn't prove much one way or the other about the intrinsic accuracy of a certain design.

I agree with you. I am only relaying that the theory, in my very limited experience, does not bring results that are worth differentiating a bullet choice for my application of hunting and a hunting rifle. But those flat base .338 160 TTSXs sure do fly well!!

I agree with you too!

I was told once by a very respected custom benchrest bullet maker that boat tails are more difficult to get consistently concentric edges of the boat tail shoulder than flat base bullets with their 90 degree base and a pressure ring.

Gee, it would seem that the one that is more accurate is the bullet type that is more accurate.

Weird..

This may have been true at one time but not any more. The king of the benchrest shooters Tony Boyer has been shooting Hottenstein bullets for quite some time, Lowell Hottenstein only makes boat tails.

At the last benchrest match I attended in May about 30% of the shooters were using boat tails, In my experience some barrels like flat base some barrels like boat tails.

Interesting. I couldn't find any photos of the Hottenstein bullets. How much of a boattail do they have?

Thanks, that explains a lot.