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Ballistic coefficient

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Post by John Willoughby 30/11/21, 07:00 pm

Was wondering where a good source is to find the ballistic coefficient of the bullets used in your videos .bullet I am going to try 1st is the ppb492450 I used a basic coefficient calculator I found and came up with .422.not to confident in the accuracy of it.also I got some swiss 3f and was wondering how would you determine the charge compared to 2f.?

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Post by earlyg 01/12/21, 09:25 am

I've also tried finding resources online to determine the BC of cast bullets. Even with the specific details of bullets listed at accuracy molds, I have found the calculators to be inaccurate (extremely wide flat noses with a higher BC than a narrow nose, etc.) or irrelevant due to the slow speeds of muzzleloaders.

So I too, would be interested in finding an accurate resource or calculator.

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Post by Admin 01/12/21, 09:33 am

Here is a link, Calculating Bullet BC is something i have never gotten in to, I have no experience with it

http://tmtpages.com/calcbc/calcbc.htm
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Post by earlyg 01/12/21, 10:30 am

Idaholewis, I have tried that calculator in the past, and had high hopes for it, but that is the one where I got strange results.  After getting the BC for a particular flat nose bullet from accuracy molds, if I then widen the nose in the calculator - I will get a higher BC, the wider I would set it - the higher the BC would go.  Maybe I'm doing it wrong, but I tried several times and with different bullets of different sizes and shapes.

i.e. - Accurate Molds Bullet Design 50-415I comes up with a BC of .27 (selecting Cast Bullets & Radius Nose), but then if I only change the Meplate or Tip Dia. from .36 to .46, then the BC goes up to .289.  When I put the Meplate or Tip Dia. to .502 (which would make it nearly a can shaped bullet) the BC rises even further to .298  

This calculator also gives other strange results with the same bullet design, such as:
Adding weight with a wider flat tip - BC goes even higher (Weight=450gr Tip=.46 BC=.313)
Lengthening the bullet with added weight and a more narrow flat tip - BC goes lower (Length=1" Weight=450gr Tip=.3 BC=.244)

Needless to say, this calculator confuses me for cast bullets..  Maybe I just don't know what the hell I'm doing.

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Post by Admin 01/12/21, 11:11 am

This BC Calculating stuff is over my head, I don’t even bother trying. My way is going to field and Shooting a Bullet at All distances and seeing exactly what it does Very Happy
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Post by EdMehlig 01/12/21, 12:01 pm

Lew, what you said works for me!  The proof is how the rifle shoots as far as accuracy and how it performs on game. Ballistic coefficient  1986740415
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Post by Waters 02/12/21, 07:34 pm

Ballistic coefficient  Img_2011

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Post by Waters 02/12/21, 07:36 pm

Here you go increasing b.c. on 50-415I

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Post by Admin 02/12/21, 09:32 pm

:09:
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Post by Waters 02/12/21, 09:35 pm

I wonder how that size is up to the G1 drag model

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Post by John Willoughby 05/12/21, 04:19 pm

Well where I live here in mt I live about 30 minutes from where the Quigley rifle shoot is held so there are quite a few guys around here that shoot the same bullets we are talking about.i was able to talk to a few guys and it sounds like most do not know what the ballistic coefficient of their bullets are.just like Idaho said they burn powder and send lead downrange to compile there data!

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Post by Waters 06/12/21, 06:51 am

As a Target shooter or long range shooter .ballistic coefficient really makes a difference in the outcome of shot placement. I believe most long range shooters are looking for a a ballistic coefficient of 0.4 in change or better (don't quote me on that) as a hunter I will not be shooting in most cases over 200 yards .I have more of a mind to be concerned with sectional density than ballistic coefficient. It's very true most of us do not know the ballistic coefficiency of the rounds we are shooting.

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Post by jcnull2305 09/12/21, 06:28 pm

It's been my experience dealing with the whole idea of BC is greatly complicated by the fact that the individual missile's BC changes with velocity (even as the missile is travelling it loses velocity, and changes the BC), and atmospheric conditions.  That's why the only true way to determine a projectile's BC throughout the entire velocity spectrum is to use radar equipment to obtain measurements.  When using the more involved ballistic computing software to obtain shot solutions, you will be asked to enter the BC across the velocity spectrum, and the atmospheric conditions in which the rifle was zero'd in order to obtain predictable (somewhat) results.  I have a ranging optic that I enter the individual cartridge information into.  Then the optic communicates with a Kestrel Elite unit via blutoof' to obtain atmospheric conditions.  The optic then compares that information with the conditions under which the the rifle was zero'd, and calculates a shot solution.

There's a more involved and pedantic explanation here, but I just realized that I want to harm myself  after reading what I just wrote, so...

Ballistic coefficient  Barney10
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Post by Tank 10/12/21, 01:48 am

I think this is why I’m getting back (way back!) to BP PRB shooting.  
I’ve always loved the ‘science’ of shooting. Loved the challenge of trying to shooting great groups at longer ranges.....ringing gongs at a kilometre sometimes more (mostly less).
But there’s something deeply satisfying and fascinating about how well this old tech works!  Not just the accuracy but the fair dinkum fun factor!  The flash, the boom, the smoke, the smell!
Don’t go beating yourself up on the science!
Get some more BP smoke in your lungs!
You know you love it regardless of BC!  Haha!
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Post by Admin 10/12/21, 11:42 am

Tank wrote:I think this is why I’m getting back (way back!) to BP PRB shooting.  
I’ve always loved the ‘science’ of shooting. Loved the challenge of trying to shooting great groups at longer ranges.....ringing gongs at a kilometre sometimes more (mostly less).
But there’s something deeply satisfying and fascinating about how well this old tech works!  Not just the accuracy but the fair dinkum fun factor!  The flash, the boom, the smoke, the smell!
Don’t go beating yourself up on the science!
Get some more BP smoke in your lungs!
You know you love it regardless of BC!  Haha!

Me to!! I love the simplicity, and on top of that i am able to get these Old Guns to shoot as good as ANYTHING out there, including my Scoped Centerfires, they Bring a BIG Smile to my Face every time i shoot them Ballistic coefficient  3355125947
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Post by Tank 10/12/21, 03:43 pm

That’s exactly what drew me here Lew!
I’ve been amazed through my own experiences with the accuracy potential these ‘old fashioned’ arms have.
Finding your videos and seeing the results of your careful work ups has been hugely interesting but also inspiring!
I’ve been an avid Capandball watcher for a long time and love the historical context but yours are real world possibilities!
I had a Lyman Deerstalker Stainless .54 that would cloverleaf 3 shots at 80 yards with Hornady Great Plains bullets but the lock wasn’t worth a pinch of crap (pot metal I swear) and eventually after a couple of trips to the smith he said ‘that’s the last time I want to see this thing.....if you’re not happy....I suggest you move it on’. I wasn’t.....so I did.
Wish there were a few more TC’s out here! Seem to work pretty well for you Lew!
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Post by Admin 30/12/21, 02:51 pm

Well fellla’s I have been playing around trying to learn this BC Calculator This morning, As to how accurate it is? I really don’t know? It is not at all difficult to use, in fact I find it easy to use

This is the Calculator i used
http://tmtpages.com/calcbc/calcbc.htm#calculator

Here is what i am Getting with my BACO Money Bullet
Ballistic coefficient  Ux00eQ5
Ballistic coefficient  Lruj6Op

Simply follow this Guide they have for the Lyman Snover Bullet
Ballistic coefficient  YlsnN9z

All i had to do was add the numbers from my Bullet above
Ballistic coefficient  PLk3uSj
Ballistic coefficient  M1ZhTQx
Ballistic coefficient  9YQyFBN


Last edited by Idaholewis on 31/12/21, 05:33 am; edited 1 time in total
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Post by Admin 30/12/21, 03:14 pm

I did the Lyman Gould as well

Ballistic coefficient  RBL8bP8

Ballistic coefficient  PsbmDta
Ballistic coefficient  2oVnxtI
Ballistic coefficient  Y1JlCFq
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Post by Waters 30/12/21, 03:42 pm

Those are pretty impressive numbers on that baco money.what's the numbers on the twist rate in the barrel you use to stabilize that?

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Post by Tank 30/12/21, 04:08 pm

They’re definitely some pretty projectiles!
I’ve got an old Lyman mould I use for my 45-70 (very similar in nose profile) runs just over 500gr with Lyman No:2 alloy that shoot beautifully with 1:20” H&R Shikari.....
Stability is another part of the science I guess.
Plenty of online calculators I spose?
Is it fair to say what would work as an adequate twist rate for a given bullet style in Smokeless should also work in BP?
I’m guessing it would be?
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Post by Buckskins&BlackPowder 30/12/21, 04:41 pm

I like to keep it simple myself!
Ballistic coefficient  Daisie10

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Post by McLoader 30/12/21, 07:42 pm

The G1 drag model is based on a military ballistic standard that was a 1lb artillery slug (as I understand it) the B.C. Of the standard slug was 1.0 . Early balisticians utilized the studies to predict trajectories and wind drifts of small arms projectiles. One thing to note is the model can be inaccurate in the transonic regime as the bullet moves from supersonic (above ~1100FPS) to subsonic. Most muzzle loaders from 0-200 yards likely operate in this regime. The bullet “sheds” the supersonic shock wave and in doing so can lose gyroscopic stability ( begin to tumble) if not adequately “spun”. This is why the drastic variety of available barrel twist rates in ML rifles. I did some studies for some “Quigley” style shooters a few years ago and found that for velocities around the trans sonic velocity region wind drift can vary pretty wildly bad news for Mr Quigley. My recommendation to those guys was to be cautious to choose carefully at what range this happens so as to optimize wind dope predictions. This meant for them carefully choosing charges and velocities so that they avoided the transition or at least had it to happen in the first 100 yds. As the models predicted less variability in drifts at subsonic speeds. Pretty interesting stuff. For hunting purposes the BC of a ML bullet to me is relevant in determining Max Point Blank range sight settings,and predicting how well I can manage wind drift for a given projectile.



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Post by McLoader 30/12/21, 08:58 pm

Sorry just wanted to complete the thought above. These ballistic models are not above anyone and you can go to Gunwerks.com or a host of others to get really good and free software. The bullet geometry methodology is not exacting, and I would never trust those figures wholly without range verification(though they are likely close) but doing this homework can save a lot of headaches and money and really help you understand the performance and limitations of your equipment.

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Post by Admin 31/12/21, 05:43 am

Waters wrote:Those are pretty impressive numbers on that baco money.what's the numbers on the twist rate in the barrel you use to stabilize that?

The BACO Big Money Bullet is for for my 1:17 Twist, i have shot it in my 1:18 Twist as well with good results Ballistic coefficient  3355125947

Here it is in my 1:18 Twist, I shot Three 3 Shot Groups here at a Ranged 100 Yards, all 3 Groups were really close to an inch.


Ballistic coefficient  DRoR98t

This is 5 Shots at the same 100 Yards, The lowest shot here was the Cold Clean Bore
Ballistic coefficient  THEAAXl
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Post by Admin 31/12/21, 05:46 am

McLoader wrote:Sorry just wanted to complete the thought above. These ballistic models are not above anyone and you can go to Gunwerks.com or a host of others to get really good and free software. The bullet geometry methodology is not exacting, and I would never trust those figures wholly without range verification(though they are likely close) but doing this homework can save a lot of headaches and money and really help you understand the performance and limitations of your equipment.

I agree, These BC Calculators will get you close, But you really need to test this stuff in the Field where it counts
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