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Thread: Boat tail vs flat base boolits

  1. #1
    Boolit Buddy
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    Boat tail vs flat base boolits

    I remember reading that boat tail boolits only give you an advantage after 200 to 300yrds. And that flat bases are better for closer ranges. Something about when the hot gases are leaving the muzzle behind the boolit.

    Can anyone tell me if this is true Or false?

  2. #2
    Boolit Master

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    My experience says that its true. I would say that its further than 2 or 300 yards though. Most short range bench rest loads use flat base bullets. My test show this too, although I shoot boat tails in my long range rifles.

  3. #3
    Boolit Master
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    i think there is more to do about twist rate and such
    Flatbase bullets are shorter so they can stabalize "better" in slow twist barrels. Some will say the flat base bullet design has more bearing surface, also like you say there is the existing gases some how influencing the boat tail more than a flat base?
    All you can do is try some testing. i shoot some 110 grain flatbase varmint bullets out of my M1 and 1903a3 they perform no better or worse than the 155/168s out to 200 . i would not hesitate to run them out to 600.

  4. #4
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    Lloyd Smale's Avatar
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    Id say over the years ive had better accuracy with flat based bullets. that said ive had some guns that shot boatails just as well. Just part of load development to me. Flatter shooting? Maybe way out there but then ive shot deer at 500 yards with flat based bullets and not a single one of them laughed at me for making the wrong choice Guess that when push comes to shove if I know im going to be faced with a 500 yard shot id rather have a rifle shooting a flat based bullet at 3/4 minute of angle then a boatail that shoots a group twice that size. I can dope for wind and elevation but I cant dope for an inaccurate load.
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  5. #5
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    The advantage of the boattail is most apparent beyond 400 yards, and it has to do with drag and high velocity.
    The higher the velocity and the number of times the bullet exceeds the sound barrier the more drag is imparted upon the bullet, and the quicker it will slow down.

    The boattail helps reduce the drag upon the bullet.
    I wish I could go into more detail but I need to go to my grandson's ball game, his team is undefeated and will go into eliminations this morning before it gets hot.
    Last edited by Hickory; 06-30-2018 at 02:34 PM.
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  6. #6
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    mac1911 nails it with; "Flatbase bullets are shorter so they can stabilize "better" in slow twist barrels."

    Otherwise with the quality of today's commercial bullets in non benchrest rifles both are potentially equally accurate. Over practical ranges the deciding factor in any rifle should be accuracy and terminal affect if used for hunting. At longer ranges the BT is ballistically more efficient and is the choice.

    Recently, on a prairie dog shoot, I found little practical difference between a FBd 55 gr bullet and a BT 55 gr bullet out to 500 yards in the .223 Remington. The FB 55 gr Varmageddon also did as well as the BTd 55 gr Blitz King out of my 22-250 out to 500 yards.

    My 30-06 M70 shoots 180/190 FB and BTd bullets with equal accuracy with the same loads. Thus I use the BTd because the are more efficient at longer ranges by retaining more velocity hence more energy. While I do try to get as close as the hunting situation allows I have, occasionally, had to make some longer range shots. Having a bullet that alllows getting the most out of it ballistically is beneficial.
    Larry Gibson

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  7. #7
    If this was about jacketed bullets the issue would be debatable. But about cast, it is undebatable. The reduction in drag shows up only at low velocity, so the range at which it does is variable, depending on such things as size of the bullet and shape at the front end. But I don't think boat-tailed bullets, comparing like with like, have ever bettered the flat-base match rifle bullets used when cast was all every target shooter had, at ranges of 1000 yards or more.

    But if the bullet is under groove diameter, a heavy flat based bullet is more likely to expand under the first impulse of the powder gases. , This was well documented in the days of muzzle-loaders, when everything had to come up the way it went down, and long range demanded something else than a true minié.

    Against this, what if your bullet is slightly over groove diameter, or your rifling is undesirably deep for this sort of work? There is a danger of finning at the rear of the bullet, and even worse, of its not being exactly the same all around. A gas-check can prevent this, but with a card wad or grease cookie it will be there when the thing drops off. The boat-tail (or indeed a rebated base) will have that finning flattened into the first fraction of an inch of its conical surface, instead of at the base.

  8. #8
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    Historically this has been more of a manufacturing tolerance issue than an aerodynamics problem with jacketed bullets. It's much easier to make a consistently flat 90 degree base from bullet to bullet than it is a boat tail as production dies wear and are adjusted. Today's run of the mill jacketed bullets are much more consistent then years' past. With FMJ it is more difficult to manufacture consistent bases due to the open base and variability as compared to soft point, HP, ballistic tip, etc. Match bullets are primarily HP for this reason, more consistent manufacturing. It's the same as us being persnickety about cast boolit bases. Stand by for onslaught of posts telling me the purpose of a JHP match bullet is to shift the center of gravity to the rear...

  9. #9
    Boolit Master pertnear's Avatar
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    I'm not sure if we're discussing cast or jacket bullets here. I have no experience with BT cast boolits so my comments only apply to jacketed bullets.

    The aerodynamic advantage of the BT bullet at very long ranges is a well proven fact. But the following is IMHO so take it FWIW.

    For a handloader, the BT bullet has an advantage of seating easier & with less chance of damaging the base. I realize that if cases are inside chamfered enough this is a non-issue, but I have seen tiny jacket shaving around a case mouth when seating FB bullets when the case mouth was too tight or the bullet got started in a bit crooked. On game animals, using standard cup-n-core, non-bonded bullets, the BT bullet has a better chance of shedding it's core as the bullet slows to a stop. Not a lot of significance to this because at that point your game animal is probably extra-dead!
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  10. #10
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    I started this thread when I started looking at the boolits from my Lee 300 230gr blackout mold. They seem to be more or less boat tailed. I may be wrong, but I don’t think this round is expected to be used at long ranges. That’s why I wonder if a flat base wouldn’t be better.

  11. #11
    Boolit Master kens's Avatar
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    Quote Originally Posted by Larry Gibson View Post
    mac1911 nails it with; "Flatbase bullets are shorter so they can stabilize "better" in slow twist barrels."

    Otherwise with the quality of today's commercial bullets in non benchrest rifles both are potentially equally accurate. Over practical ranges the deciding factor in any rifle should be accuracy and terminal affect if used for hunting. At longer ranges the BT is ballistically more efficient and is the choice.

    Recently, on a prairie dog shoot, I found little practical difference between a FBd 55 gr bullet and a BT 55 gr bullet out to 500 yards in the .223 Remington. The FB 55 gr Varmageddon also did as well as the BTd 55 gr Blitz King out of my 22-250 out to 500 yards.

    My 30-06 M70 shoots 180/190 FB and BTd bullets with equal accuracy with the same loads. Thus I use the BTd because the are more efficient at longer ranges by retaining more velocity hence more energy. While I do try to get as close as the hunting situation allows I have, occasionally, had to make some longer range shots. Having a bullet that alllows getting the most out of it ballistically is beneficial.
    Can you tell how much of a difference in velocity of the FB vs BT bullets? I mean even out there 500yd and beyond, how much difference in velocity is there, really?
    Is there a means to test this?

  12. #12
    Boolit Master
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    Didn't the French or Germans come up with the boat tail design for improved indirect machine gun fire at troop concentrations? Spitzer ogives and boat tails showed up around the end of the 1800's. I remember seeing Hornady , Speer and Sierra bullet charts when there were no boat tails available on their bullets.
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  13. #13
    That would be the French Balle D of 1898, which I believe was both the first spritzer bullet and the first boat-tail, and while there were machine-guns at that time, I think an exaggerated idea of the range at which military rifles would be used was more what they had in mind. Senior commanders remembered how, insofar as France earned any credit for the Franco-Prussian War, much of it came from the superior range of the Chassepot over the Prussian needle-gun. Indirect fire was mostly used at targets such as bridges and crossroads, where the bullets arrived with no sound above the 1914-18 background noise, and men would take cover at the first shell. You can't move a crossroads.

    But the Balle D was solid bronze, and I think at least finished on automatic lathes. Wear and tear on swaging tools wouldn't apply, a situation which has about been solved by tungsten carbide or nitriding.

  14. #14
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    Quote Originally Posted by kens View Post
    Can you tell how much of a difference in velocity of the FB vs BT bullets? I mean even out there 500yd and beyond, how much difference in velocity is there, really?
    Is there a means to test this?
    Ballistic tables can tell us the difference. Modern ballistic formulas where we can enter a known BC, muzzle velocity and zero range are the best. They can easily provide the difference in down range ballistics (trajectory, retained velocity and energy) given an equal muzzle velocity and zero range.
    Larry Gibson

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  15. #15
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    I use the Jacketed BT just because they are easier to seat.....I have lost some finger skin using the FB before.
    My cast boolits are seated in flared cases.
    Tom
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  16. #16
    Boolit Man metricmonkeywrench's Avatar
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    That same discussion just came up on the Midsouth Shooters blog.

    http://www.mssblog.com/

  17. #17
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    The accuracy difference is debatable. My Heavy barrel Savage 110 will consistently shoot 5 shot groups under 9/16" @ 100 with Sierra 55 gr BTSPs (some way under). My 6mm likes 100gr. Hornady BTSP's and shoots under MOA as well. I don't know if flat base would shoot better and I really don't care. In both cases they shoot well enough for their intended purposes.

    I have heard that BT's are prone to losing jackets easier than FB. On varmint bullets it is moot, and, at least on deer sized animals, I have never had a problem with the BT's. In fact the only time I had trouble with a bullet splashing on a deer and not penetrating was with a 154Horn. FB from a 7mm Rem MAG. The shot was close and the bullet was moving over 3100fps at impact and exploded on a rib. It killed the deer, but jacket and core didn't make it half way through broadside.

  18. #18
    Quote Originally Posted by Rick Hodges View Post
    The accuracy difference is debatable.
    Boat-tails giving superior accuracy is, although people as knowledgeable as Sierra use them almost universally for bullets in the style of he MatchKings. But boat-tails giving inferior accuracy is a theory which doesn't get a look-in.

    What the really dedicated benchresters do with rifles and cases is often of very limited relevance to what the rest of us need. Not so, however, what they do with bullets. The improvement in accuracy from the old "2moa? What are you complaining about?" days is mostly down to them, for some barrels and rifles have always been made as well as the best of the present day. Unless they have changed of late, they seem pretty sold on boat-tails.

  19. #19
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    I don't understand how a bullet can break the sound barrier more then once.
    Quote Originally Posted by Hickory View Post
    The advantage of the boattail is most apparent beyond 400 yards, and it has to do with drag and high velocity.
    The higher the velocity and the number of times the bullet exceeds the sound barrier the more drag is imparted upon the bullet, and the quicker it will slow down.

    The boattail helps reduce the drag upon the bullet.
    I wish I could go into more detail but I need to go to my grandson's ball game, his team is undefeated and will go into eliminations this morning before it gets hot.
    Soldier of God, sixgun junky, Retired electrical lineman. My office was a 100 feet in the air, closer to God the better

  20. #20
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    Quote Originally Posted by Lloyd Smale View Post
    I don't understand how a bullet can break the sound barrier more then once.
    Lloyd

    Bullets, airplanes, rockets and other projectiles can "break the sound barrier" (which is simply a term for speed)/velocity) several times. It's called MACH I, MACH II, MACH III, etc.
    Larry Gibson

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check