Boat Tails

[rodwha]

It seems larger bore bullets just don't come in a boat tail design, though the Hornady 147 grn 9mm bullets do. Does velocities between 1400-2000 fps not benefit from this?

I've been contemplating a .50 cal barrel for my sidelock for something that I can hunt across fields with out to 200 yds, and what I come up with as the best projectile is an aerodynamic Hornady bullet (.430 or .451") in a sabot.

I prefer to cast though and wondered about a custom mold with a moderate meplat and a boat tail in a lighter weight so as to be able to have a point blank that works out to distance (175-200 yds). I'm wondering if a boat tail does enough to concern myself with it.

[Geezer in NH]

Bevel base not boat tail

Boat tails start to work after 3-500 yards.

[rodwha]

Bevel base not boa tail

Bevel base instead of boat tails for slower bullets? This works better or a boat tail just doesn't improve things?

With OAL vs twist rate the lack of a boat tail would certainly increase the mass a little, and I'm assuming a beveled base, were I to use it in a sabot instead of paper patched, would work better in the sabot itself.

On the other end I've wondered about the how much a wider meplat works against the aerodynamics as I've read of people with less than stellar results with pointy lead bullets. I figured a compromise might be in order.

[dragon813gt]

The 147 grain bullet you mentioned is bevel based. It's not a boat tail design. The bevel base is there due to the case taper.

[rodwha]

I see. Looks like a typical boat tail to me as a beveled base makes me think of the bullets meant for a sabot. But then I'm a bit ignorant in some regards.

[Whiterabbit]

What they all said, but if you absolutely insist on a boat tail, then you can buy such a 50 cal beast in a Barnes bullet. TEZ bullets are boat tail .451's in a 50 cal sabot.

They shoot fast and true, and the petal arrangement is impressive at 2000 fps to say the absolute least. It would be devastating.

I would expect nothing less than perfect for nearly $1.50 PER bullet.

[rodwha]

The cost is certainly something I look at. When lead can cost as little as $1/lb and I can cast nearly thirty-six 195 grn or twenty-five 285 grn bullets it puts thing in a different perspective to me.

With that said I've always like Hornday bullets both for their ingenuity and cost. And so I've looked at what I can create at Accurate Molds to do about as well as what I can buy from Hornady.

And cost certainly means something to me because I shoot what I shoot while at the range. That would get expensive quickly.

[Whiterabbit]

well, if you want to shoot (for example) GC boolits in a sabot without the GC and want something that will cradle the base a little better than a standard flat bottom sabot, you can buy Barnes boat tail sabots directly by calling them, they are something like 10 cents a pop. Just another option.

[rodwha]

My understanding (I've not tried any yet) is that in general sabots work better with slightly beveled bases compared to a typical flat based bullet. Not exactly sure why.

[rodwha]

I've actually wondered how well a .458 X .50 cal sabot would work with my 285 grn WFN bullet that drops at .456" for my Ruger Old Army. But this wouldn't be a long range deal...

[swathdiver]

Do you have the book, "The Muzzleloading Caplock Rifle" by Ned Roberts?

One would do well to read that and his other, similar tomes. Those fellas did what you want to do over a hundred years ago Rodwha.

[rodwha]

I do not. The only BP weapons book I own is Percussion Revolvers by Cumston & Bates.

[Omnivore]

I believe the ogive and meplat are more critical to aerodynamics than the base. Study the shapes and BC (Ballistic coefficient) of modern bullets in loading manuals, and I believe you'll come to the same conclusion. In some cases you'll find essentially the same bullet, one with a flat base and one with a boat tail. The boat tail will have a higher BC, but not by much.

Another place to look, and I've been harping on this for some time, is to the long range BPCR shooters. They shoot at up to a thousand yards with black powder, and while the pressures involved would likely erode a percussion nipple, the BPCR community is a good place to look for long range shooting solutions. In short; you will notice that they tend to use very long, very heavy-for-caliber bullets and tolerate a very arched trajectory, but they get some amazing results.

Idaho Ron on this forum had done quite a lot in "hot-rodding" his sidelock percussion rifles for long distance hunting, so I'd check out everything he's written on the subject. He seems to have it pretty well figured out, and his work is more up your alley, so to speak.

Bevel base bullets are more for easy seating in metal cases than anything else. Even in rifle cartridges the easy seating is promoted as one of a boat tail's desirable features. In a pistol (and I and others have done the math) the bullet's BC is really not a significant factor since you're not shooting multiples of 100 yards distance, plus the velocities are lower. BC matters more and more the higher the velocity and the greater the distance.

You will notice by looking at the ballistics tables, that the bullet dumps its energy far more quickly at higher velocities. Thus, in modern, high velocity rifle shooting, a higher BC is often more beneficial than a little bit more launch velocity. At BP velocities it's somewhat less of an issue.

Also; good luck in getting ballistic coefficients for muzzleloading bullets. I haven't seen any.

Getting back to modern rifles; you will note that bullets intended for hunting are usually not the highest BC bullets. Some of them are downright poor. The reason is that the hunting bullets tended to have short ogives and wide meplats for impact trauma. I say "tended" (past tense) because some of the newer polymer tip hunting bullets have both a high BC and good initial expansion.

I hunt with round ball out to 100 yards (I use a 100 yard zero, but the longest shot I've taken on game so far is 85 yards), so I can't say much about high BC bullets in a muzzleloader. I have however spent a lot of time studying the loading manuals, shooting modern rifle out to 700 meters, and studying the effects of BC on various calibers using an exterior ballistics computer program.

[rodwha]

I've talked with IdahoRon a few times and his work is excellent.

I was hoping to skip big heavy bullets because of the rainbow trajectory. My preference is to have a point blank system out to distance which I was hoping to extend out to 175-200 yds. The best thing I could come up with was an aerodynamic .43 cal bullet in a sabot for a .50 cal.

At best it seems a Hornady .44 mag flex tip was about ideal or the 250 grn SST as I wouldn't get enough velocity to use a .444 flex tip.

But I prefer to cast if I can and wondered about a smaller meplat of maybe .22-.25" and utilizing a boat tail. But if the boat tail doesn't do enough there's not much point in reducing the mass I guess.

[Good Cheer]

How about a design with a truncated cone wide flat point nose and an identical tail end?

[Tackleberry41]

I really doubt at the ranges a muzzle loader is used at you would see any difference worth the effort to get more aerodynamic bullets.

I know one issue I see with some sabots being sold, is the velocities the manufacturer is expecting them to run at. I was looking at some 40 cal ones recently, and Hornady was basing everything on a 150gr max charge. A ton of velocity, but who even comes close to using that much powder? And Hornady tends to design a bullet for a set velocity range for it to expand properly, so would that 40 cal bullet do much expanding at realistic charge levels?

My TC inline did pretty good accuracy wise with just some 44 and 45 cast bullets I had left over from loading. A bag of 100 sabots for $9 is way better than what some of the sabots are running these days. I can't justify $29 for 15 sabots, one of the super wombat ones the local place had on the shelf. May not perform as well as advertised if not charged to the levels the manufacturer tested them at, sort of defeats the purpose of paying the extra money.

[charlie b]

True boat tails are designed for supersonic velocities. It has to do with reducing drag and where the shock waves are on the bullet. Angles are critical. You bullet needs to stay supersonic most or all of the way to the target.

At black powder velocities you will not see much, if any, benefit from a true boat tail.