In my mind a round ball (especially in .22 for better production control by the larger size) should.....
1. Travel farther(flatter trajectory) in the same time frame as a pellet of any shape having the same weight(mass),...... from skin turbulance of a roughened surface.(less air friction)
2. Retain gain-twist spin longer, again from this same skin turbulance and lessor amount of air friction.
3. Be more accurate from the above.....
4. Be easier to load...
5. And further gain from not having a parachute dragging it down called a skirt.
6. And most importantly....has minimal surface area of any other form.
So why are most shooters using multi-shaped pellets at sub-sonic velocities when nature likes round?
---Addendum to question. ---I would like to hear physics/aerodynamic arguments as to what properties of pellets "could" make it superior to balls in accuracy and trajectory. My reference is the science of golf ball developement for one, and minimum surface of a sphere for another.
Questioning whether pellets are superior to balls.
Could: The three things you have overlooked are the following;
Sectional Density
Ballistic co-efficient
weight (unless someone makes a hollow round ball)
If the sphere were superior, the very concept of the bullet (or similar projectiles) would have dissapeared years ago, and we would still be firing cannon balls.
Ryan
Sectional Density
Ballistic co-efficient
weight (unless someone makes a hollow round ball)
If the sphere were superior, the very concept of the bullet (or similar projectiles) would have dissapeared years ago, and we would still be firing cannon balls.
Ryan
Many years ago I experimented with lead round balls in my .308Win rifle at short distances. Accuracy was very good at 20 yards and typical 5 shot groups were a ragged hole, when bullseye powder was used. The casted .310 lead round ball only weighed about 48 grains while the typical hunting bullet for the .308Win is 150-180 grains. The jacketed hunting bullet has better accuracy at long ranges, better performance on animals, superior ballistics, etc. A small .308 caliber copper jacketed lead ball still wouldn't have the needed weight or ballistics for big game hunting.
Airgun pellets seem to weight about the same as lead balls in typical calibers (.177-.25). The typical .177 caliber pellet is around 7.9gr (average) and the Gamo lead BB is 8.2 grains. The H&N/Beeman lead BB is 8.02 grains. The .25 caliber lead BB is 23.61 grains, according to H&N/Beeman. These weights are typical for accepted pellet weights in these sizes.
If weight isn't the issue with lead balls in pelletguns then there must be others reasons for preferring pellet projectiles.
The shuttlecock design of the typical pellet has a purpose. The flared skirt catches air and helps keep the pellet stable in flight. Ideally, the hollow skirt also slightly expands and forms to the barrel, if needed. This allows a pellet to function in bores with slightly different sizes. A wide skirt will easily squish down in a tight bore because of the hollow design.
Lead balls must be fitted to the barrel to get best accuracy. We don't have that option when purchasing balls (i.e. 4.48, 4.49, 4.50, 4.51, 4.52). I realize that many pellets are available in different head sizes but the majority are not. I don't think Crosman offers choices and, as far as I know, RWS only offers choices in the match WC pellets.
The performance of the pellet vs the lead ball speaks the loudest for a preference reason. Take a tin of lead BBs and a tin of quality pellets and shoot groups at 25-50 yards using a rifle that shoots 700-900fps. The facts will speak. I know this doesn't give you the reasons for the differences but a bit of web searching might answer those questions. Sorry, I don't have those answers.
BTW, good questions.
HTH,
Todd
Airgun pellets seem to weight about the same as lead balls in typical calibers (.177-.25). The typical .177 caliber pellet is around 7.9gr (average) and the Gamo lead BB is 8.2 grains. The H&N/Beeman lead BB is 8.02 grains. The .25 caliber lead BB is 23.61 grains, according to H&N/Beeman. These weights are typical for accepted pellet weights in these sizes.
If weight isn't the issue with lead balls in pelletguns then there must be others reasons for preferring pellet projectiles.
The shuttlecock design of the typical pellet has a purpose. The flared skirt catches air and helps keep the pellet stable in flight. Ideally, the hollow skirt also slightly expands and forms to the barrel, if needed. This allows a pellet to function in bores with slightly different sizes. A wide skirt will easily squish down in a tight bore because of the hollow design.
Lead balls must be fitted to the barrel to get best accuracy. We don't have that option when purchasing balls (i.e. 4.48, 4.49, 4.50, 4.51, 4.52). I realize that many pellets are available in different head sizes but the majority are not. I don't think Crosman offers choices and, as far as I know, RWS only offers choices in the match WC pellets.
The performance of the pellet vs the lead ball speaks the loudest for a preference reason. Take a tin of lead BBs and a tin of quality pellets and shoot groups at 25-50 yards using a rifle that shoots 700-900fps. The facts will speak. I know this doesn't give you the reasons for the differences but a bit of web searching might answer those questions. Sorry, I don't have those answers.
BTW, good questions.
HTH,
Todd
In general agreement if WEIGHT is a factor....
Granted, the choice of forms other than round turns on the issue of weight...(for hunting, killing), seating....(reforming of the skirt), and steering ability of the skirt acting as a stablizer at the rear.
But these things are not the real issue.
If the ball has sufficient mass for the game(or target) and seats well in the lands and grooves for gain twist without blow-by (thus eliminating the skirt functions in a pellet)..... The smallest possible surface area MUST have the least amount of drag.....and the ball MUST travel faster and straighter over a given distance.
Arguments to better bullet forms for killing are not addressing accuracy arguments inherent in round ball form.
Where I am heading here is of two purposes.... round for speed & accuracy,..... and surface finish for least drag. Like a dimple pattern on golf balls.
I now am in contact with Cibles of Canada, trying to obtain two more styles of balls from them..... H&N graphite & copper plated. This will give me a total of 4 types so far... Lobo, Ballistic products, and H&N. I intend to get some of every manufacturer in 22 caliber for shooting comparison. Meanwhile I would like this discussion pursued...... LarryS
P.S. I have searched the web for info on this subject....day's 'n days. There are a lot of opinions... but facts are not being offered to support their statements.
But these things are not the real issue.
If the ball has sufficient mass for the game(or target) and seats well in the lands and grooves for gain twist without blow-by (thus eliminating the skirt functions in a pellet)..... The smallest possible surface area MUST have the least amount of drag.....and the ball MUST travel faster and straighter over a given distance.
Arguments to better bullet forms for killing are not addressing accuracy arguments inherent in round ball form.
Where I am heading here is of two purposes.... round for speed & accuracy,..... and surface finish for least drag. Like a dimple pattern on golf balls.
I now am in contact with Cibles of Canada, trying to obtain two more styles of balls from them..... H&N graphite & copper plated. This will give me a total of 4 types so far... Lobo, Ballistic products, and H&N. I intend to get some of every manufacturer in 22 caliber for shooting comparison. Meanwhile I would like this discussion pursued...... LarryS
P.S. I have searched the web for info on this subject....day's 'n days. There are a lot of opinions... but facts are not being offered to support their statements.
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papaburger
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Re: In general agreement if WEIGHT is a factor....
That is not true. Please seeLarryS wrote:The smallest possible surface area MUST have the least amount of drag.....and the ball MUST travel faster and straighter over a given distance.
http://www.lerc.nasa.gov/WWW/K-12/airplane/shaped.html
Only the frontal area affect Cd.
You will see that airfoil has less drag than sphere at a subsonic airspeed.
see also
http://www.ae.su.oz.au/aero/fprops/intr ... ode11.html
Its seems dimples on golf balls are for further drag reduction by separation of boundry layers.
How about a compromise design such as a rifle bullet (sharp point, boat tail, or rebated boat tail (to avoid blow-by). Good for supersonic and subsonic ?
In a simple way, not too technical, I did a test between Gamo round ball 8.2gr vs RWS R10 .177 8.2gr
The results were tested on velocity in 500's and 700's at 40 ft.
Also gun vise is used.
the round ball velocity is lower by 2 to 5 fps on both cases.
POI trajectory at 500's is 1/4" different and 700's NO different.
The results were tested on velocity in 500's and 700's at 40 ft.
Also gun vise is used.
the round ball velocity is lower by 2 to 5 fps on both cases.
POI trajectory at 500's is 1/4" different and 700's NO different.
Hi Larry,
Great topic! Thanks for keeping it alive and not giving up on the issues.
Okay, we will assume the round ball has a perfect bore fit... as with the pellet.
The typical pellet has very little friction with the barrel. That is another reason for the "waist" design. The frontal area of the pellet, know as the head, should not engrave in the rifling but rather slide on the lands. The rear area, known as the skirt, will engrave when the fit is proper for the bore. If you look at a pellet you will notice that the actual area of contact is quite small at the skirt and head.
As everyone here knows, I am fond of test results over opinions/guesses. Larry, I have a test for you. Hopefully you have the needed equipment.
You can use a break/barrel springer rifle or a barrel that is detached from an airgun. You will also need a push rod such as a 1/8" wooden dowel or a .177 caliber cleaning rod and also a bathroom scale. Clamp barrel in a vise or have someone hold it for you. Insert a 4.50mm pellet into the breech end of the barrel and use the scale to push the pellet completely through the barrel. Watch the scale weight to see how much pressure is needed. Repeat the procedure for the 4.50mm round ball. Let's see which has more resistance.
The lead round ball should cut through the air better than a wadcutter pellet. A dome pellet or pointed pellet would obviosuly have a better ballistic coeffiecent than the end of a round ball. If you look at the BC of various pellets you will notice that a slight change in the head shape will sometimes result in a projectile that has a much better BC. A round ball always has the same shape, while pellets are often made to take advantage of head shape. A wadcutter is the exception but they were designed for 10m target work and cutting clean holes in paper at short distances. I think a domed pellet such as a JSB Exact will have a flatter trajectory than a round ball. Maybe someone can do this test at 10-20-30-40 yards for proof purposes.
As for killing, a domed pellet should have better penetration that a round ball (shape advantage). Wadcutters were not designed for hunting and hollowpoints require much power to properly perform.
Hunters sometimes move to the .25 caliber pellet for more weight and a the larger wound channel it offers. The light .25 pellets weight slightly over 20 grains but the heavier versions are over 30 grains. The .25 round ball is only 23.6 grains. To get more weight from the ball the length would have to be stretched and then you get more friction... unless you create a waist and hollow the back of the projectile for forward balance... then it's close to a pellet design.
I realize that this discussion is not about hunting potential but rather accuracy and velocity comparisons. My above point was a bit OT.
The game of Field Target is about accuracy with pellet rifles. Distances will go out to arond 50 yards and extreme precision is needed. These guys take every step possible to get the most out of their shooting rigs and ammo. They weigh and size ammo, use high mag scopes, and do countless tests on their rifles to find the best hold positions, etc. If round balls were the most accurate projectile out to 50 yards then you could be guarrantied that these guys would be using them. If round balls were the most accurate projectile then they would also be used in the air silhouette competitions. I assume we can accept these facts but we are researching to find the reasons for the advantage of the pellet for accuracy and velocity.
For 10m accuracy you may find a proper fitting round ball to be okay. If you have a barrel that matches the rifling twist to a round ball then you may increase accuracy further.
Exact sizing of round balls and mass production for companies might not be an easy thing, when compared to the forgiveness of a hollow skirted pellet... but let's assume we have a company that has no issue with profits and makes round balls in micro step increments. This would give us a good chance at finding the exact size for our barrel. I think a domed pellet still has the velocity retention advantage (higher BC), penetration advantage, and long distance accuracy advantage. Hopefully we can get some tests done to create proof.
Todd
Great topic! Thanks for keeping it alive and not giving up on the issues.
Okay, we will assume the round ball has a perfect bore fit... as with the pellet.
The typical pellet has very little friction with the barrel. That is another reason for the "waist" design. The frontal area of the pellet, know as the head, should not engrave in the rifling but rather slide on the lands. The rear area, known as the skirt, will engrave when the fit is proper for the bore. If you look at a pellet you will notice that the actual area of contact is quite small at the skirt and head.
As everyone here knows, I am fond of test results over opinions/guesses. Larry, I have a test for you. Hopefully you have the needed equipment.
You can use a break/barrel springer rifle or a barrel that is detached from an airgun. You will also need a push rod such as a 1/8" wooden dowel or a .177 caliber cleaning rod and also a bathroom scale. Clamp barrel in a vise or have someone hold it for you. Insert a 4.50mm pellet into the breech end of the barrel and use the scale to push the pellet completely through the barrel. Watch the scale weight to see how much pressure is needed. Repeat the procedure for the 4.50mm round ball. Let's see which has more resistance.
The lead round ball should cut through the air better than a wadcutter pellet. A dome pellet or pointed pellet would obviosuly have a better ballistic coeffiecent than the end of a round ball. If you look at the BC of various pellets you will notice that a slight change in the head shape will sometimes result in a projectile that has a much better BC. A round ball always has the same shape, while pellets are often made to take advantage of head shape. A wadcutter is the exception but they were designed for 10m target work and cutting clean holes in paper at short distances. I think a domed pellet such as a JSB Exact will have a flatter trajectory than a round ball. Maybe someone can do this test at 10-20-30-40 yards for proof purposes.
As for killing, a domed pellet should have better penetration that a round ball (shape advantage). Wadcutters were not designed for hunting and hollowpoints require much power to properly perform.
Hunters sometimes move to the .25 caliber pellet for more weight and a the larger wound channel it offers. The light .25 pellets weight slightly over 20 grains but the heavier versions are over 30 grains. The .25 round ball is only 23.6 grains. To get more weight from the ball the length would have to be stretched and then you get more friction... unless you create a waist and hollow the back of the projectile for forward balance... then it's close to a pellet design.
I realize that this discussion is not about hunting potential but rather accuracy and velocity comparisons. My above point was a bit OT.
The game of Field Target is about accuracy with pellet rifles. Distances will go out to arond 50 yards and extreme precision is needed. These guys take every step possible to get the most out of their shooting rigs and ammo. They weigh and size ammo, use high mag scopes, and do countless tests on their rifles to find the best hold positions, etc. If round balls were the most accurate projectile out to 50 yards then you could be guarrantied that these guys would be using them. If round balls were the most accurate projectile then they would also be used in the air silhouette competitions. I assume we can accept these facts but we are researching to find the reasons for the advantage of the pellet for accuracy and velocity.
For 10m accuracy you may find a proper fitting round ball to be okay. If you have a barrel that matches the rifling twist to a round ball then you may increase accuracy further.
Exact sizing of round balls and mass production for companies might not be an easy thing, when compared to the forgiveness of a hollow skirted pellet... but let's assume we have a company that has no issue with profits and makes round balls in micro step increments. This would give us a good chance at finding the exact size for our barrel. I think a domed pellet still has the velocity retention advantage (higher BC), penetration advantage, and long distance accuracy advantage. Hopefully we can get some tests done to create proof.
Todd
Last edited by TCooper on Thu Dec 01, 2005 6:31 pm, edited 1 time in total.
LarryS wrote:The smallest possible surface area MUST have the least amount of drag.....and the ball MUST travel faster and straighter over a given distance.
The smallest possible (overall) surface doesn't mean much when it comes to aerodinamics. Think about how the air will flow around the shape of a round ball, compared to a proper airfoil shape. The round ball creates a lot of turbulance behind it, and this creates drag.
I'll say no more - others have already mentioned this.
Read those webpages that were posted, there's probably some good information there.
Hi TCooper....
You have a number of good points TCooper.
I have examined the lands & grooves marking on balls and I do find that the "band" for lack of a better word, is far wider than a pellet. On this I grant you the point....resistance would be greater for a ball in the barrel, which translates "Maybe into a significantly" lower muzzle velocity. Certainly initial resistance would be higher.
And again I grant you another point.... manufacturing a ball with enough precision to compete with a precision pellet would be far harder to control by the manufacturer because only the ball weight, diameter, and surface texture can be used to control its precision whereas a pellet allows variation of nose, waist, skirt, weight, diameter, and surface texture as a combination to achieve the desired qualities for shooting without any special emphasis on trajectory, etc.,
Your other points I need to reflect on more......
It is not likely that I will find the perfect ball with the skin texture I want..... but I will search for what is closest.
I still hold that the reduced surface area of a ball will overcome some or all of the drawbacks you have cited against the ball. It would be interesting to find some data on the laminar air flow characteristics of pellets.
Match shooters probably stay within the generally accepted pellet styles looking only for more attention to detail in that style.... I doubt if any really pursue balls at all simply because it is not a readilly obtained ammo of precision. This does not mean the potential for a superior ammo does not exist...... Just like the penetration tests conducted between a pointed pellet and a ball by a well known Air rifle supplier.... where the ball blew away all contenders by the wound channel you mentioned.
Much more needs to be pinned down to resolve all doubt...... and we both know that properties of air craft wings etc., have nothing to do with this except Bournelli's principle when we get around to that.
Addendum- side note on ball penetration vs pellets.....
http://pyramydair.com/site/articles/pel ... und-balls/
I have examined the lands & grooves marking on balls and I do find that the "band" for lack of a better word, is far wider than a pellet. On this I grant you the point....resistance would be greater for a ball in the barrel, which translates "Maybe into a significantly" lower muzzle velocity. Certainly initial resistance would be higher.
And again I grant you another point.... manufacturing a ball with enough precision to compete with a precision pellet would be far harder to control by the manufacturer because only the ball weight, diameter, and surface texture can be used to control its precision whereas a pellet allows variation of nose, waist, skirt, weight, diameter, and surface texture as a combination to achieve the desired qualities for shooting without any special emphasis on trajectory, etc.,
Your other points I need to reflect on more......
It is not likely that I will find the perfect ball with the skin texture I want..... but I will search for what is closest.
I still hold that the reduced surface area of a ball will overcome some or all of the drawbacks you have cited against the ball. It would be interesting to find some data on the laminar air flow characteristics of pellets.
Match shooters probably stay within the generally accepted pellet styles looking only for more attention to detail in that style.... I doubt if any really pursue balls at all simply because it is not a readilly obtained ammo of precision. This does not mean the potential for a superior ammo does not exist...... Just like the penetration tests conducted between a pointed pellet and a ball by a well known Air rifle supplier.... where the ball blew away all contenders by the wound channel you mentioned.
Much more needs to be pinned down to resolve all doubt...... and we both know that properties of air craft wings etc., have nothing to do with this except Bournelli's principle when we get around to that.
Addendum- side note on ball penetration vs pellets.....
http://pyramydair.com/site/articles/pel ... und-balls/
Last edited by LarryS on Fri Dec 02, 2005 12:02 am, edited 1 time in total.
Papa burger, that is a good URL.
Interesting about the Cd of a sphere being 0.07-0.5 That is tending to support what I am yapping about...
The parachute skirt behind a pellet would be a much more complex frontal surface equation I think unless they discount partial vacuums creating cavitation of enormous proportions... Thankyou, LarryS
Interesting about the Cd of a sphere being 0.07-0.5 That is tending to support what I am yapping about...
The parachute skirt behind a pellet would be a much more complex frontal surface equation I think unless they discount partial vacuums creating cavitation of enormous proportions... Thankyou, LarryS
Larry, my experience with roundballs in a PCP is they shoot the same velocity as the equivalent weight pellet.
Men, Larry is not talking about BBs and really they do not compare to real lead rounds at all.
I am very interested in this Larry so stay on it.
If I can help in any way let me know okay?!
Walter...
Men, Larry is not talking about BBs and really they do not compare to real lead rounds at all.
I am very interested in this Larry so stay on it.
If I can help in any way let me know okay?!
Walter...
Walter