A possible variant might be related to breaking the sound barrier. A round ball is not the most ballistically effective design and encounters significant bow wave issues when breaking the barrier. Shooting velocities that break the sound barrier could happen at different points along the trajectory, depending on the velocity of the load. It could possibly affect POI. That being said, most of us probably can't out shoot the result. My .50 caliber flintlock shoots very accurately with loads ranging from 65 to 110 grains of 2FF. Seventy five grains of 2FF produces the tightest groups most consistently. The search for the "sweet spot" is half the fun.
Velocity affect accuracy ?
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Those shots were fired for the group only, the aiming point was the small diamond in the center of the target
Very true and it happens twice if you're shooting long range once at the muzzle and again when the projectile drops below sonic.
Erwan
50 Cal.
[USER=49056 said:
Did you hear something about a Gaussian curve?
longcruise
70 Cal.
Shucks, I've never heard of a gaussiajn curve. What's it tell us and what data goes into it?
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I bet you have heard of the bell curve? Same thing but your professor prefers the ,"Gaussian curve"!
longcruise
70 Cal.
Erwan
50 Cal.
In this case, you can compare the relationship between velocity and accuracy using a Gauss curve. To begin with, and before choosing the most appropriate load according to calibre and base load, and therefore the bullet velocity, you must follow this curve. Initially, the velocity is not good and the dispersion is high. If you increase the load, and therefore the velocity, your dispersion cone will begin to decrease, it will decrease more and more until it reaches the highest point of the curve, and if you continue to increase the velocity, your accuracy will begin to decrease, and the higher the velocity, the more you will be on the wrong side of the curve: your dispersion cone will deteriorate more and more until it returns to the lowest point, as if you hadn't worked on your load and had stayed on the minimum basic load, which is most often 1 calibre for 1 grain, for example 45 grains for a .45 calibre, which happens to be the most common starting load before fine-tuning the load, and therefore the velocity/accuracy ratio, to find the load that suits your gun.
I don't know if I've made myself clear, as I often find it difficult to explain certain basic technical principles in your language.
Erwan.
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Stykbow
50 Cal.
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I never thought about applying a bell curve to shooting, but it would work. I use those on occasion in my work. Back to the question of a lower velocity being more accurate in ML’s. Have you ever noticed how small most folks powder charge is on here? They say it’s more economical and it is, but it’s also generally very accurate for those guys. I get it, but it’s just not in me to shoot 45 or 50 grains of powder in a 50 cal ML.
A "bell curve" is a normal distribution of data points. In the case of ML load development, it would be a graph of the offsets of the impact points from the aim points versus loads used. It's a statistical measure of qualifying the significance of the results. It's got nothing to do with projectile trajectory. A broad curve means the impact results were distributed over a wide variation, while a steep sharp curve means the impact results were distributed over a narrow variation. Obviously, the narrow variation is a more desirable result. The "peak" of the curve is the mean (aka "average") of the entire group of measurements, and a "standard deviation" is taken from the width of the curve at a certain point, where the number of data points under the curve equals a defined mathematical formula ("sigma"), and which may be interpreted as a measure of the width of the distribution of those data points. Obviously, a smaller standard deviation is a more desirable result, and signifies greater consistency of points of impact. The peak of the curve would signify where the load with the most impacts within the standard deviation, and thus the best load for accuracy and consistency.
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Erwan
50 Cal.
I understand exactly what you mean, but two or three things are still very different: target shooting, hunting, and last but not least, pleasure.
Today, I used 36 grains of French BP (PNF1) 3Fg with a Pennsylvania .45 (.445 balls and .013" patches) rifle at 50 meters just for target shooting. This is a very low load but extremely accurate and precise for this rifle, that permits today a group of 1.45x1.45" and 97/100 points (MLAIC rules). That way is just for the precision and too soft for pleasure and/or hunting, it all depends on what you expect from BP flintlock shooting and for what you do it...
I wonder if passing through the speed of sound would affect accuracy? A lot of funny stuff happens at that point. Like if the muzzle velocity was just over the speed of sound. I think muzzleloaders can shoot that fast, but I'm not sure.
And I'll add shape and surface of the bullet - E.g., golf balls have all those dimples all over them to break up laminar flow so that trailing vortexes don't slow them down and make them go all over the place as much (if I recall correctly).
Hey - that gives me an idea: maybe I should put dimples all over my flintlock round balls
I wonder if anybody has ever tried that. My guess is they have tried it, and it didn't work, which is why round balls are not dimpled. Oh, well, there goes another great idea :-/
And I'll add shape and surface of the bullet - E.g., golf balls have all those dimples all over them to break up laminar flow so that trailing vortexes don't slow them down and make them go all over the place as much (if I recall correctly).
Hey - that gives me an idea: maybe I should put dimples all over my flintlock round balls
I wonder if anybody has ever tried that. My guess is they have tried it, and it didn't work, which is why round balls are not dimpled. Oh, well, there goes another great idea :-/
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Erwan
50 Cal.
Not exactly, when I'm shooting at 100 meters with my Pedersoli Tryon and 500 grains bullets (target shooting) the speed is over 400 meters/second and the sound is at 340 m/s (~1115 Fps). Ok, those bullets are paper-patched, but they fly over the sound speed with any loss of precision. There isn't the real problem: Frequently the speed is around 600 m/s (also paper-patched bullets) for Black Powder Target Rifle Creedmoor Championships and the precision is at the "Rendez-vous" in long-range...
longcruise
70 Cal.
That was pretty clear. I doubt if I'll try it though!
That's the key. What's it to be used for.
I know a few guys who shoot matches and vary the powder charge based on the range. 8 have several rifles that shoot accurately up and down the powder scale. So, a project I'm going to do when the weather warms up and the wind calms down. My thoughts are to zero at 50 yards with a mid range charge and then shoot various charges at 25 and 100 to find the ones that shoot to poa. If accuracy is good I'll give it a try in a match.
I know! Just hold over or under, right? That's what I've done for a long time but with aging eyes maybe this would improve scores by having POI match POA.
The problem I have with holding over the target at 100 yards is that the target becomes hidden by the barrel so I go from using 60 grains at 50 yards to 75 grains at 100 yards and am able to use the same POA.That was pretty clear. I doubt if I'll try it though!
That's the key. What's it to be used for.
I know a few guys who shoot matches and vary the powder charge based on the range. 8 have several rifles that shoot accurately up and down the powder scale. So, a project I'm going to do when the weather warms up and the wind calms down. My thoughts are to zero at 50 yards with a mid range charge and then shoot various charges at 25 and 100 to find the ones that shoot to poa. If accuracy is good I'll give it a try in a match.
I know! Just hold over or under, right? That's what I've done for a long time but with aging eyes maybe this would improve scores by having POI match POA.
longcruise
70 Cal.
That's exactly what I'm going to try to do. Thanks for the encouragement.
Those are called chewed balls. Using two rasp the ball is pimpled all over. Some say they work great others ain’t impressedI wonder if passing through the speed of sound would affect accuracy? A lot of funny stuff happens at that point. Like if the muzzle velocity was just over the speed of sound. I think muzzleloaders can shoot that fast, but I'm not sure.
And I'll add shape and surface of the bullet - E.g., golf balls have all those dimples all over them to break up laminar flow so that trailing vortexes don't slow them down and make them go all over the place as much (if I recall correctly).
Hey - that gives me an idea: maybe I should put dimples all over my flintlock round balls
I’ve never tried them
i have been handloading since i was a kid in 1967, velocity can defiantly a difference in group size/accuracy. a lot of variables go into it,,,,,,,,,,,,,,,,,
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You sound like my teachers! Your description is on target!
There is sound truth in it. As a military match shooter who trains offhand with .36 caliber Pennsylvania long rifle flintlock, there are some important considerations to take into account.
Caldwell Tack Driver Filled Bag Shooting Rest
Is a rest that only secures the rifle within the area of the action and lock area being supported. Without and tension being applied. This is good for testing loads and preparing to file your front sight to the correct elevation. NEVER support a long rifle on the barrel. Perhaps any rifle.The long rifle was designed, rather brilliantly, to be fired accurately offhand. Thus the early invention of the swamped barrel for heavier calibers.
The stock on most any rifle is the most influential variable to the rifles accuracy as it can and will affect the harmonics. Thus we now have the modern chassis and free floating barrels.
This affects even the first shot. Contrary to popular belief.
The long rifle always shoots more accurately without supporting the barrel. For testing loads and filing your front sight, rest only back at the transition or closer to the lock. The balance point of the long rifle is its best attribute and is the true reason why it’s accurate. The rifle will shoot better than you with the right load.
Shooting it offhand is how you get good at hunting with it. Good at shooting regardless.
With even practicing twice a week you can be an expert. There is a problem with men and shooting that prevents them from becoming experts at shooting. Once they get a load and instead of concentrating on form and shooting, they start “chasing the worm”. It’s as if finding the perfect load is their most entertaining and fun challenge. Round and round they go. Instead of looking at it like an instrument of skill and hunting tool, they start viewing it as a potential “sniper” rifle. A modern day phenomenon that men have to pursue some optimum ballistic utopia. First off, you aren’t a good enough shot as you haven’t trained yourself at offhand shoot twice a week. Everything is off a bench as you continue to “chase the worm”.
My second point. If you can’t push down ten consecutive shots down your barrel, your barrel is either still rough on the inside or you tried to make a sniper rifle out of your instrument of efficiency. Your rifle.
Overly thick patches and some mythical, magical lube. Even olive oil will work or any kind of fat. I use moose milk and soak my patches or strips in it. If you have to drive your ball down the barrel, you might have gone further than you needed to get a good load. Stop supporting the barrel at the bench.
That’s my 2 cents. I’m sure there will be some that disagree with me.
If your group fits in the size of a fist from 50 to 100 yards offhand, you can kill anything. Are you shooting at horse flies?
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I have heard of people dimpling their balls. I believe someone heard that golf ball flew better dimpled and said,"why not lead ball"?
