Not to start a debate, but I wonder if someone can explain this to me.

I have been dinking around with about 5 or 6 different bullets. These are the Sierra 52 grn HPBT, the Nosler 52 grn HPBT, the Hornady 50 grn SX, the Hornady 50 grn Vmax, the Nosler 50 grn Ballistic Tip, and the Barnes 50 grn VLC.

In all most all of the loads, hands down, the flat base bullets fly better(.22-250, .223, .222). In some rifles, I noticed there are 12 lands and in other rifles there are only 6. The rifle with six lands doesn't seem to mind the boattails, but the rifles with 12 lands won't shoot 'em at all (1.0 MOA). I don't know if that would matter or not. Perhaps someone has some understanding concerning this.

Someone told me once that boattails fly better at long ranges. I don't know if that is an old wive's tail or what.

The other thing I have to ask is what is a good group at 200 yds? Would olympic class be .25 MOA? The reason I ask is that sometimes I get great groups and other times I don't. I just wonder what is possible and what the real standard is. Perhaps that will get a lot of mixed responses, but I am considering this in the context of bench shooting with HB rifles.

As far as the BTs being better at long range are correct in my opinion. I have noticed it personally when using a Sierra MatchKing, I believe it's due to the fact that they are more aerodynamic, and therefore lost velocity at a slower rate than a flatbase bullet.
The reason why the flatbases are better at short range is they don't have the time to really lose all that amount of velocity. It's also a simple theory, the flatbases are more accurate because their are less angles. In other words with less angles there is less things to go wrong.
The current 200 yard IBS HB 5 shot group record is .1610 inches or 0.08 MOA, but 1/4 MOA is outstanding in most cases.

Boat tails generally have a higher BC than flat based bullets. Therefore, they have less drag and lose velocity slower than low BC bullets.

However, boat tails are easier to upset when they leave the muzzle. This is due to pressure irregularities caused by the most minor imperfections with the muzzle crown. Any crown damage will cause a pressure differential as the boat tail leaves the muzzle.

If you have a target guns that shoots flat based bullets but doesn�t seem to group well with boat tails, have the muzzle crown re-cut. This will generally solve the problem.

"We always want to find a boattail bullet that shoots well in our rifles."

boattails are more complicated in construction than flatbase, since .224 bullets are more sensitive to asymmetric uneveness, good .223 boattail becomes a gun specific matter. In larger calibers, boattail have more chance to shine.

[This message has been edited by Pyrotek (edited 02-05-2002).]

I haven't tested this in any systematic manner, but my impression, based on some shooting of both flat base and boattail bullets, is that some calibers do not shoot boattails as well as they shoot flatbase bullets. In particular, the .300 Weatherby does not seem to like boattails.

I'd be interested in seeing whether anyone has done systematic testing to see whether bullets that are otherwise alike, except that one is a boattail and the other is a flatbase, produce different levels of accuracy. To do such a test well it would be necessary to test a number of calibers and also a number of different rifles of the same caliber. In other words, answering this question thoroughly would not be at all easy.

But there's no question that boattails have considerably higher ballistic coefficients than corresponding flattails, meaning that the boattails retain velocity better, especially at longer ranges (300 yards +). Also, they are sexier looking!

To answer the original question, .25" at 200 aggregate will WIN most bench rest matches.

Once you get to the .5 MOA range, getting better gets very much harder, very fast. I've only shot ONE group "in the ones" in my life. To do it consistently, takes match bullets, match barrels, etc, etc, etc. FWIW, Dutch.

In a .30-338 I have, shooting the flat based lighter bullets seemed to work better at 100 yards. On the whole they got better groups. Past 100 yards there is no contest. The boattails have it by a mile. Not having much experience with the lighter calibers in a target situation, I have been told that sometimes the flat based bullets work better in some AR-15 type firearms. If flat based bullets work in your rig, why are you worried? If your results are inconsistent, you may not be positioned the same everytime, there may be a small seemingly insignificant proceedure in the reloading process you are doing or not doing, your rifle may have a loose screw somewhere, your aim may have the rifle slightly canted, or you may not be doping the wind properly. Pay attention to what you do and the next time those bug holes appear remember everything you did up to that point, and repeat it. If you can shoot flat based bullets in tight groups while competing, consistently, I will be jealous. Good luck.

The Germans discovered the benefits of the boattail bullet in assessing long range machine gun fire around the time of WWI. At the time, all bullets had flat bases.

A bullet leaves the barrel at greater than the speed of sound. When the flat based bullet drops back thru the sound barrier, it causes it to upset and destroys its accuracy. It was discovered that if the bullet had a boattail, it reduced the vacuum behind the bullet, and reduced the degree of upset when the bullet dropped below the speed of sound. For machine gun fire, which was used at what we'd call extreme ranges, the boattail was determined to be more accurate.

Generally speaking, flat based bullets are more accurate that boattails because of how it leaves the barrel, and the effect of gases leaving the barrel on the bullet. This is particularly true if the bullet reaches its target before it drops subsonic. This generally occurs around three hundred yards.

For a while, machine guns were loaded with boattails and other ammo was loaded with flatbased bullets. However, it was cheaper to produce one type of ball ammo, and the bean counters won. (Don't they always!) The boattail would shoot from a rifle well with in a MOA of Frenchman, so why not make only one bullet?

A boattail bullet will be more accurate at longer ranges, but generally has less accuracy that a similar flatbased bullet inside three hundred yards. (Tactical use of machine guns in those days called for firing them 1000 yds at target in defilade.)

Anyway, that is what I read along time ago, and it is consistent with the observations you are reporting. Ku-dude

tsmysak,
Boat tail bullets are longer than flat base bullets and some 22 caliber rifles have rifling twist rates that are not compatible with the longer bullets. This may not be your problem but it may be part of your problem. Boat tail bullets also seat deeper in the case which can raise pressures. Higher pressures can cause problems with barrel harmonics.
That being said, some of my most accurate 30-06 loads have been with boat tail bullets. If you work up the loads carefully you have more control over the variables in the loading process. I have never been able to change from one bullet type to another without working the load up all over again.

PaulS

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stay safe and live long!

I can't believe I get to use the information on this forum for free!

Other forums seem to focus on which is better, Budweiser or Miller . . . 1911 or Glock.

Wow. You guys were all over that one.

I went out last night and did yet another little test in a long series of tedious experimentations. It is difficult to determine at best and probably would require the employment of a professional statistician.

I did get the boattail to finally shoot well. At 100 yds with a .22-250 Weatherby, I put the first three shots in one hole (I mean 1 hole too), however, my hands got real cold and I blew the group in my excitement. So I added to my elation, a good deal of uncertainty. (I hope you all find this as humourous as I do.) I should have stopped at three rounds, but you lose all bragging rights if you do that.

One thing I have found is that the boattails are very sensitive to the charge weight. I have shot 35.0, 35.5, 35.6, 36.0, and 36.2 grns of IMR 4064 and the only one that shoots is the last one. That is a mystery at best. Perhaps it has a great deal to do with the crown and barrel exit as someone mentioned. Would it be a negative if the charge was fully consumed before the bullet had traversed the barrel? I am finding that slower powders are far more robust...??Just another thought...

Genghis - Free You mean that you have not received your invoice this month???? Saeed, please make sure you bill Genghis for this month�s forum use!

First of all, I am not crazy and it�s only 9:30 a.m. in Dallas so I�m not completely drunk,,, yet. I think the elements involved here are rate of twist in barrel, bullet design, barrel crown, and MUZZEL BLAST.

I think we can all agree that it takes a period of time for the bullets to stabilize themselves during flight. I have proven to myself that excessive muzzle blast contributes to the �yaw� of the bullet as it leaves the barrel and is pronounced in boat tail style bullets.

This revelation came to me while working on my 4 year olds first �big boy� gun a few years back. His first rifle was a Remington model 600 in 223 which he could shoot like a house-a-fire. He then wanted to shoot my 22-250, I think because it had a 6 � X 20 monster scope on it. He didn�t shoot as well and told me it kind of kicks. Soooo, I put a KDF on it for him. He then shot it like a champ. I figured it was just a young kid flinching. NOT! Understand, I am loading this 22-250 up with Berger boat tails at 4,000+ f/s with slower powders and a lot of muzzle blast. One day I am at the range shooting this rifle and the guy at the bench next to me bitches that the muzzle blast is blowing him off his bench, so I remove the KDF. My groups at 100 yards went to hell. I put the KDF back on and the groups tightened up. Nothing else changed.

My conclusion: boat tail bullets, which are not truly stabilized as they leave the muzzle, can have their �yaw� increased by excess muzzle blast.

My solution: My 22-250, 243, 240Wby Mag, 257 Wby Mag, and 7 STW all wear KDFs. I shoot boat tails in all of them.

Shoot safe,
Mike

A number of years ago the Army did a study of flat based vs boattail bullets. In a rifle shooting boattail bullets, it's accuracy noticably improved to around 3,000 rounds, after that there was slight improvement up to 10,000 rounds. When shooting flat based bullets, accuracy peaked at 3,000 rounds and gradually detererated after.

I shoot Highpower (Service Rifle)which requires boat tail bullets to achieve accuracy at medium "long" range. (600yrds)

However, the last word in accuracy comes from the bench rest crowd. (100 - 200yrds)
If you look in the magazines such as Precision shooting (which caters to the bench rest crowd)or talk to some of the BR guys, you will notice that NONE of the bench rest shooters use boat tail bullets.

For shooting at short distances i.e. 100-200yrds flat base bullets are the most inherently accurate. This, incidentally is where most measurements and comparisons are made. (everyone wants to know what your rifle will group at 100yrds)

Thus, if your going to punch paper at close range, go with the flat base. If you are trying to reach out there and touch something. the boat tail will serve you better.

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J.W.
Hero of the Hapless
Master of the Obvious

TSMYSAK, aaaaahhhhhh yes, the old three thru one hole and the next two on the paper........somewhere. When you have practiced as long as I have, and shot as much as I have, you will get past that to four thru one hole and the fifth on the paper...........somewhere. I think my problem is that it is hard to squeeze the trigger and pat myself on the back at the same time.
My knee jerk response is it seems most of my rifles like flat base bullets better. But then, I rarely shoot beyond 300yds, except sage rats and ground hogs. For varmints, I use the least expensive bulk bullets I can buy.

It's too bad the major manufacturers don't give us the best of both worlds--rebated boattails.

This is my first response to this forum. I was going to respond to the match king debate but it was the same stuff over and over and over.
The way I heard it flat base bullets are much easier to manufacture to closer tolerances then boat tail bullets making them more accurate in the short range. Boat tails because of the better ballistic coefficient eventually become more accurate over a longer range say over 250 yards or so do to two factors. One they hold velocity better and two better BC also makes them much less affected by cross winds. I was telling a friend this same scenario adding I didn�t know why the BC had such an effect on cross winds. His answer was that the bullet actually has a cylinder of air being pushed in front of it that i.e extends the length of the bullet giving it more surface area to be affected by the wind.
Having fished for trout I knew what he was talking about. Picture a rock out in a stream. The trout will sit right behind the rock, this everyone knows, but they will also sit directly in front of the rock in a section of water that slows down because it can�t get around the rock fast enough. A wad cutter rock would have the most slow water in front and in back followed by a spitzer shaped rock, followed by a boat tail rock. The boat tail rock because of the swept rear end dumps the water back behind itself making it the most efficient at letting air get around it and having a smaller cylinder of air in front.

Regards
Leadbottom

The next step will be asking for Base Bleed bullets to inprove BC yet further!

(As seen on long range artillery shells)

Deerdog, I refuse to ask you what the hell is a "base bleed" bullet. (sounds like a hemroid)

Leadbottom -

Quite the interesting response, and a noble analogy as well ! I also think your friends' theorem is brilliant ! Allow me to add to his pearl of wisdom - As the bullet travels through the air, it compresses the air in front of it. As the bullet approaches 750 mph and breaks the sound barrier (depending of course on the delta of your actual elevation and sea level), it will condense the moisture in the air as well as it passes through the sound barrier. I would postulate that these elements, as well as the "button" of dense air in front of the bullet itself play a collective part in the flight of the bullet, especially in the presence of a cross-wind, which I might add will affect the flight path in a linear fashion in direct relation to the cross-wind speed.

In support of all those that posted that boat-tails (especially spitzer form factors - smaller frontal cross section, more aerodynamlc, lower coeffecient of drag) are more accurate at longer distances, based on pure physics, they will.

Upon what am I basing all this? Purely on engineering theory and the laws of physics. What level of practical experience do I have with boat-tail vs. flat-base bullet trajectories and accuracy? Virtually none. Why have I posted all this drivel? You think the shuttle was designed and launched based on emperical data? Hell no. A bunch of engineers did it based on engineering theory and the laws of physics, and, as in most major engineering efforts - a good amount of luck. Whether they want to admit it or not.

In closing, I would draw the conclusion that if one wants a very accurate round up to a 200 yard point of impact, I'd go with a flat-based, sub-sonic round in order to remove as many external-influence factors as possible.

So much for theorem. I'm a FNG in the reloading/shootong arena. What do the rest of you REAL shooters out there say? I recall the words of a wise reloader/shooter I know: "Screw the theory, you go with what works!"

Long on words, short on experience,
Dino

My most accurate loads in all of my rifles have used ballistic tips which are boattails.This has been at 100 yards as well as at 400 yards.

I haven't done enough back to back testing between flat base and boat tailed bullets in any of my rifles to make a stand on this issue, but picking up on a point made by Pyrotek, I shoot a lot of 55gn V-Max (which are flat based) in .22/250; someone recently gave me a few 50gn V-Max to try. Not enough to make a worthwhile evaluation but what was clear to me is that the 50 gn is the same bullet as the 55gn but with a boat tail shaved/shaped on.
Which rather begs the question - which came first (and was the product of intensive design and development), and which was the by-product?

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tikka 3 barrels

Not to drag this on and on, but there are a lot of variables we are talking about here. The ballistic tip / Vmax bullets are finely pointed as well as longer, which I understand promtes a better BC. The Vmax is a good flying bullet and I shoot the 50grn in one rifle that will maintain a ragged hole at 100 yds with that bullet. That load, however, doesn't seem to like Sako rifles, which I was really amazed. Everybody knows that Sako rifles shoot all loads well *grin*. So now I am finding that I have to have a different load for each rifle, which I always knew anyway. But it would be nice if I didn't have to maintain a large database just to have to keep every rifle shooting well.

The whole reason for my original question was I have one rifle that absolutely will not shoot boattails, which I have some really great loads for. On the very best day it might manage 1.5 MOA at 100 yds. I was really disgusted and was trying to sell the rifle. Then I tried a cheap old flat based bullet in the rifle with a less than ideal load and shot about a 0.3" group at 200 yds (only once though). I had the idea that something was wrong with the rifle if it would not shoot boattails, but perhaps that simply is not true.

I am curious concerning the 55 grn Vmax. Perhaps the loss of material for making the tail takes away 5 grns of bullet weight??? so that would be a cheap side by side test now.....Are there any sponsors???

Each week a small bunch of us head for the range where we shoot small rocks at distances from 425 yds to 1100 yds. I shoot 300 Win Mag, 80 gns of H-1000 with 178 A-Max or Sierra 2220C. The HPBT is the accurate one at 600 yds plus. Consistant on a 12 inch target at 1100 yds. Wind always makes it fun since at 8000 ft altitude, it comes from three directions on path over small canyons. Keeps it interesting. Blueowl

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No nation shall be both ignorant and free-it never was-and never will be.

Ok, from what I gather, you'd be better served with a boat tail when shooting long distance because they are disrupted less when entering subsonic speeds.
I just figured on a ballistics calculator a .224" 55gr Vmax(flat base)with a MV of 3600 fps is still traveling 700 fps above the sound barrier at 500yds. So in therory a boat tail is of no benefit in this scenario out to 500 yards. Am I correct or way off on this?

Chris

Yeah I know, go out and see which shoots better but I'm at work ya know?

Cisco,
You've got it. As I said earlier, Boattails have an advantage way out there where mg's fire at massed infantry.

Dino,
Remember the bullet is supersonic when it departs the barrel. The upset comes when it slows down to subsonic, as Cisco reports about 400-500 yds depending upon the cartridge and bullet.

It is "accepted" that flatbased bullets settle down faster and fly truer inside three hundred yards, all other factors notwithstanding. See comments about varmit and target bullets below.

Regarding certain "new" BT's, in the reloading article in "Handloader" ref. in another post about the sonic transducer gismo that can check a bullet for voids, it was mentioned that Nosler had purchased one of these for quality assurance testing. Hornaday probably also has one.

If these devices are being used upon bullets used for varmit and target shooting, this should be one of the reasons for better "boattail" accuracy. They are better made and tested before they leave the plant.

Because of the limits on hunting distances, hunting bullets are not as subject to these requirements. This is one of the reasons BT's have become so popular as hunting bullets because of their exceptional accuracy for a hunting bullet. They are not well received for heavier, African animals where partitions still rule supreme. Ku-dude

Let's clarify this a bit:

Keeping the bullet stable when it goes transonic is a huge advantage for the boattail bullet at really long range (depending upon the range and velocity of course). But it is not its only advantage.

At long range anything you can do to increase the BC of the bullet is an advantage, at any velocity.

Adding a boattail increases the bullet's BC. At long range, that is an advantage (assuming the rifle shoots them well).

For example, let's consider three bullets--30 cal Sierra 180's. One Round Nose, one Spitzer and one Spitzer BT all launched at 2900 FPS.

At 400 yds, here's the wind drift from a 10 mph crosswind:

SPBT: 10.8
SP: 13.6
RN: 21.8

Say there's only a 1 mph wind (realy just a variable air movement--you wouldn't even feel it as a "wind" at all). Assuming the worst, your 1/2 MOA rifle, instead of shooting a 2" group, shoots a 6.36" group with the RN, 4.72" with the SP, 4.16" with the SPBT.

That doesn't sound like much, but remember it was for a basically "no wind" condition. Now do the same math for a light 2-3 mph variable breeze or a 5-7 mph wind. You can see that a small accuracy advantage for a lower BC bullet at close range (if that's the way your rifle shoots them) will disappear rather quickly at longer ranges.

Another advantage--retained energy:

SPBT: 1942
SP: 1702
RN: 1257

It gets worse the farther you shoot. At 600 yds:

Wind drift:

SPBT: 26.0
SP: 33.5
RN: 52.8

Energy:

SPBT: 1439
SP: 1167
RN: 778

This is why people that shoot at long range use the highest BC bullet they can find.

While there is a nebulous advantage to a boat tail bullet, I have heard that advantage was sold to gain what was really a advantage in manufacturing. The boat tail being ever so much easier to start into a case mouth.

More energy, more momentum, less wind drift, shorter time of flight, more advantageous centre of gravity, more ease of reloading, less chance of bullet heel damage..... the list goes on and I will take a boat tail over a flat base any day. The advantages are real and proven. Now if you tell me you don't like the way a boat tail looks, and you need to like the way a bullet looks before using it, I can't argue with that

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Gerard Schultz
GS Custom Bullets