long range bullet nose

[kokomokid]

I think now I have a good place to start testing as far as powder and wad but have a question on the bullet. What is the difference between the money bullet nose and the Prolate and Elliptical ? Also what weight / length bullet would you shoot in a 45-17 twist barrel?
Good to see KW on the mend , I met you briefly at the TX state shoot.

[Don McDowell]

Biggest difference in those bullet noses comes down to basically personal preference,especilly when we're talking blackpowder ballistics..
The thing I've found with the 45-70 is the amount of "horsepower" available,, that 2.1 case only allows for so much powder capacity and keeping the bullet weight at or below 520 grs helps the longrange shot placement.

[BrentD]

kokomo-
the Money bullet has a hemispherical nose. There are several variants of that shape but they all have hemispherical noses. I think most Money bullets have secant ogives instead of tangent ogives. However, to some extent all tangent ogives become secant to some degree when the bullet bumps up.

Most bullets that are described as "elliptical" are not (in addition to being 3D and an ellipse being only 2d). They also often have hemispherical noses, though usually of a smaller diameter.

Prolates are exactly what they are described to be, a three dimensional version of an ellipse with two equal radii. The term Prolate simply serves to distinguish them from bullets that are called elliptical that are not. The successful prolates have radii in a ratio of 4:1:1, hence a 411 Prolate is defined for any caliber you wish but with that ratio of radii. I shoot them in both .45 caliber and .38 caliber. All the prolate bullets out there now have tangent ogives.

.45-70s have plenty of powder space - even bordering on too much actually.

As for length. With an 18 twist 1.46" is good to 1000 yds, and 1.51" is okay at 1000 but can get a little squirrelly. With a 16-twist, the 1.51" is the cat's meow at 1000. Length isn't everything but for a 17 twist, I'd probably stay South of 1.48". Better a little too short than too long.

[kokomokid]

Thanks Brent.

[Lead pot]

kokomo

This goes into a little more then what Brent said. http://www.corbins.com/bullets.htm#secant click on the highlighted links and that will explain it farther. They might be jacketed bullets, but this also goes with the lead bullets.

[BrentD]

There could be a few confusing points between what I posted and what Corbin writes. For instance, not all tangent ogive bullets are spitzers - which he implies in the way he writes about spitzers (a bullet design that might bear revisiting for bpcr), but there is a lot of really useful information on that website for those interested in bullet design and construction. I did a lot of business with him, and his brother also, but casting is way more effective.

[Lead pot]

I pretty much quit swaging bullets except for the .30 calibers and a few jacketed bullets for the .444 marlin and the .50's plus the hand gun bullets.
With the quality moulds that are now made my two swaging presses are pretty much sitting idle.
I still save the cast rejects I get from cold moulds and use those for cores for swaging the .444 Metfort/Gibbs bullets.

[BrentD]

Yup, you can get a heck of a lot of fantastic quality moulds for the price of one set of swaging dies and for way way less time. I sold all my swaging gear and made a tidy profit on it. Haven't regretted it except when I was forming some .38-55 into .32-40 and wished I had my old Corbin SII press for all the leverage it had.

[kokomokid]

Yep, just trying to get a start point from the people that can shoot PP. If I get a mould that will NOT work, it wont be the first one.

[Don McDowell]

I'ld suggest starting with a .444 diameter bullet and 8# paper. BACO's moulds are good. They are smooth enough finished that many times you don't need to open the blocks to get the bullet out, just cut the sprue point the bullet base down and a bit of a shake and out comes them pretty bullets... Just don't do that over the lead pot, you'll experience the "lost bullet" casting method..Great fun but not much for production numbers [smilie=l:

[Kenny Wasserburger]

Yeah I looked real hard at Swaging figured out casting was a much cheaper route. And thanks Kokomokid.

KW.

[ResearchPress]

I posted these pictures of some 19th Century British bullets and ammunition on another thread here, but thought they may be of interest here too.

http://www.researchpress.co.uk/pics/bullets1.JPG
http://www.researchpress.co.uk/pics/bullets2.JPG

From left: the first two are .45 Whitworth bullets as sold by Whitworth, Eley and maybe others. The central bullet is .46 and for a Gibbs-Metford. These all come from the same riflemans range box from the muzzle-loading era. The two bullets on the right are also Metford and from a later (breech-loading) period.

http://www.researchpress.co.uk/pics/cartridge1.JPG
http://www.researchpress.co.uk/pics/cartridge2.JPG

The leftmost cartridge (from the headstamp) is Westley Richards No. 2 Musket. The two on the right are Gibbs No. 1.

David

[kokomokid]

I was suprised to find a photo online showing a 508 grain 411 prolate bullet with a BC of .443 compared to a sharps replica of 539 grains with a BC at .500. I would have thought the prolate would have had a higher BC ?

[BrentD]

kokomo, the prolate probably does have a higher, considerably higher BC. I've measured them before but I don't have my books handy to cite what the numbers are. The .443 number looks way way low. It is also, coincidentally the diameter that I make the bullet. Perhaps there was some number swapping that occurred in the typing of whatever you are looking at. I usually figure their bc are between .50 and .55 but honestly, it takes a lot of careful shooting to really get good numbers. Do you have a link?

[kokomokid]

Thanks for the info as I have already ordered a prolate bullet mould and you have helped lower my blood pressure this morning.

[Lead pot]

I tried to work up a 10 shot BC using the .45 Danielson 513 gr Prolate bullet setting up two chronographs up at 15 yds and 215yds but never got the job done. Killed the second sensor on the third shot. :shock::bigsmyl2:

[Lead pot]

Thanks for the info as I have already ordered a prolate bullet mould and you have helped lower my blood pressure this morning.

Who made your mould?

[kokomokid]

The mould is on order with Gayle Brooks.

[Lead pot]

I have one of Steve's .44 prolates. Good mould and a great shooting bullet.

[kokomokid]

Well maybe I had my senior moment for the morning. After a revisit to said page and what Brent said it would appear that the prolate bullet has a BC of .508 not 508 grains. Now where did I put my coffee cup?

[BAGTIC]

Many calculate, estimate, and guesstimate bullet B.C. but the only way to know for sure is by measuring them over extended ranges, Today that is done with Doppler radar. B.C. varies continuously with velocity. A bullet does not have a single B.C. Anyone who has read Bryan Litz's books of long range shooting and seen how much discrepancy exists between published B.C. and real world measured B.C. will never believe advertised B.C. again.

[Lead pot]

Bagtic the only problem is, the Doppler Radar is seldom used for the bullets we shoot with black powder for accurate data. :)

[Gunlaker]

Well maybe I had my senior moment for the morning. After a revisit to said page and what Brent said it would appear that the prolate bullet has a BC of .508 not 508 grains. Now where did I put my coffee cup?

I'd b surprised if I was not 0.5 or better. When using the JBM Ballistics software for the Money bullet launched at 1350 fps I found that using 0.5 predicted significantly higher sight settings than I experienced at distance. ( Part of that is because I think the G1 drag curve is not a good approximation at the lower speeds experienced at the greater distances ). I imagine that the prolate is the same or better with respect to aerodynamics.

Chris.

[BrentD]

FWIW, a buddy of mine is switching from grease groove money bullets to a 504 gr Prolate in his .45-70. He has found that sight elevations from a 200 yd zero to reach 800 is much less with the latter bullet. I was surprised because I have never measured super high BCs for my bullets (always done over 100 yds), but that is in comparison to internet BCs which are, I believe, vastly, vastly inflated by a few folks. I don't think a prolate will be over .55 BC at best. Regardless, it will simply shoot championship accuracy.

Brent

[Gunlaker]

I've never tried measuring the BC using two chronographs. I've just been using the JBM ballistics software and adjusting the BC numbers until they "best fit" the sight settings, while factoring in weather conditions. There is likely significant uncertainty in he numbers, but I've found that 0.5 was a pretty decent fit for my 535gr GG Money bullets IIRC, but with the PP bullets to 800m, the software predicted 10 minute higher sight settings than I actually needed.

I'm guessing that the prolate bullet might be a touch better, but only because my .38 PP bullet needs less elevation to go from 100m to 200m than any of my .45 cal Money bullets shot at similar speeds. That again is a pretty crude guess though :-)

In the end, I bet that in real world conditions with top class shooters, that no one would notice a practical advantage with one over the other. Probably they'd both work well enough to win when used by someone better than me :-)

Chris.

[Don McDowell]

One thing none of the ballistic calculators can take into account is mirage and wind, either or both can change the elevation setting needed.
It's not uncommon for a paper patched slick to need less elevation on a sight staff than a grease groove bullet in the same cartridge. It can be anywhere from a few minutes to as many as 15-20 minutes less for a paper patched bullet.

[Gunlaker]

Don, it' pretty easy nowadays to make a ballistic calculator that takes into account the wind. I wrote one ( it's actually a work in progress still ) and it'll allow you to modify the wind at any point in the trajectory as many times as you like. Nowadays it's no big deal to recompute everything 10,000 times a second if you like. How closely you can get it to match reality is another thing of course :-).

I wrote it to see if I could get better predicted sight settings for my rifles than I get with the JBM software, and for curiosities sake. I've been toying with making it into a bpcr computer game, but that's a much bigger job.

Chris.

[Don McDowell]

Chris I don't know which program Dick Savage used to use, but he would run all the data thru the thing, show up at the gong match in Alliance and the darn thing would be awfully close. I've used the one Hornady has on their web pages, and it doesn't do to bad of a job.
But still none of that will speak to us like the actual trigger time.

[Gunlaker]

Yeah that's a fact. It'll be a long time coming before anyone wins a black powder match with a computer :-). Chris.

[BrentD]

Chris, what language are you writing your code in?

[Gunlaker]

Brent I'm using C#, although I might switch to C++.

The code I'm writing is not very sophisticated, I'm just integrating the equations of motion from McCoy's book using an RK4 integrator and the G1 drag tables he includes. It's just a 3 DOF simulation right now but I will add spin drift to it at some point in time when I figure that part out.

My plan is to add some code to perturb the G1 drag curve to see how well I can make it match my sight settings. I have a feeling that it's probably just a matter of reducing the drag a bit at the lower velocities. I haven't shot enough at longer ranges to have a lot of data though.

Chris.

[BrentD]

that sounds like fun. I have been teaching myself Python as a poor alternative to Pascal. I'm beginning to think I should have just thrown in the towel and gone on to C++.

the problem with data from longer ranges (and even some sorter ones) is that there are almost certainly several different winds between you and the target. Most of them, you have no idea are even there. So, the variance in the data are hard to ascribe to anything in particular.

I'm about to head out to Oak Ridge for a match. It has some especially interesting winds in that the bullet flies over a gully and is way above the flags when shooting from the 1000 yd line. Pretty much a guess what the wind is up there, but at least it is probably less turbulent.

good luck with the code writing.

[Gunlaker]

Python is a neat, but strange language. I used it maybe 15 years ago for a little bit. It was definitely interesting. Nowadays for small applications C# might be the best way to go, although C++ has a definite performance advantage depending on circumstance.

I know what you mean regarding unseen winds. The 800m gong at Heffley Creek is more than 200 feet higher than the shooting line and we have some very interesting terrain that usually causes the wind flags to point in opposite directions in the afternoons. It's anyone's guess what's happening way above the flags, but I'm sure you are correct about less turbulence. In that case I bet there is an advantage to the guy who can shoot the fastest :-). My .45-110 seems to work reasonably well there, although I'm the slowest on the line with my PP bullets.

Chris.

[Lead pot]

:) Shooting fast for Brent is not a case :) I have spotted for him and he sure makes me curl my toes at times before he breaks a shot during switchy conditions :)

[BrentD]

Ah yes, there is something to be said for breaking a shot fast, but there is a lot more to be said for breaking a shot on target. I don't muff many, darn few, but I did muff one the last time I shot long range nationals. It would have been a 100-5x for national record but I pulled it out into the 8 ring at 3 o'clock and told my spotter so before the bullet arrived at the target.

The way it goes. This coming weekend, I'll be shooting the Long Range game with muzzleloaders - really a combined, mid/long range match, 200,300, 600, 1000. It is a "call your own wind" game and one that is slow just because it is with muzzleloaders. Last year I had 90-5x in the bag at 200 with the last shot to go. I took an extra couple seconds and shot a 9 at 9. It was a wind that came by while I was in the gun. My spotter and one other guy saw it and they knew what would happen. Too bad, they said that would have been a record if I had taken a 10 or better with it.

I'm a slow shot, but I think it works for me.

[Lead pot]

Brent.

There are a lot of last shot muff shots if one likes to admit it or not. I had a last shot muff shot at the Quigley when I shot a 41 that would have place me above the 13th place I finished at :) Hmmm what do they call it when you muff a shot??????? :)

I will be shooting at Effingham next weekend if I can get away.

[Sharpsman]

These look like shooters:

https://farm8.staticflickr.com/7634/17062353761_e19b163ff2_b.jpg (https://flic.kr/p/rZK2k8)KAL 45 PP 1.55 Elliptical_zpsm8ibmf9j (https://flic.kr/p/rZK2k8) by Sharps45 2 7/8 (https://www.flickr.com/people/61286670@N08/), on Flickr

[BrentD]

The one on the right should work, but it is dangerous to judge a bullet's potential from a picture. In the end, it is the mathematics that count.

[Lead pot]

They look like my .44's. :smile:
The one on the left is the KAL .432 505 gr elliptical and the one on the right is my Brooks mould .433 485 gr Prolate.

http://i704.photobucket.com/albums/ww43/Kurtalt/.44%20bullets_zpstxyadnnp.jpg (http://s704.photobucket.com/user/Kurtalt/media/.44%20bullets_zpstxyadnnp.jpg.html)

[Chill Wills]

Hey Sharpsman, What twist are you shooting a 1.55" bullet?


These look like shooters:

KAL 45 PP 1.55 Ellip (https://flic.kr/p/rZK2k8)tical_zpsm8ibmf9j (https://flic.kr/p/rZK2k8) by Sharps45 2 7/8 (https://www.flickr.com/people/61286670@N08/), on Flickr

https://farm8.staticflickr.com/7634/17062353761_e19b163ff2_b.jpg (https://flic.kr/p/rZK2k8)