Introduction

This article is designed to answer those questions honestly.
If this subject matter interests you, please read the ENTIRE article and follow-ups before you send me e-mail.  The article touches on physics, but is not meant to be a college course in Dynamics.

A note about Ball Spin
We all know that backspin will affect a paintballs trajectory, but spin is outside the scope of this article because most paintball guns do not have bent barrels, and I feel that bolt design will do very little to produce spin.  Spinning paintballs can also have adverse affects on accuracy, due to the irregular shape, size and weight of paintballs.     Time will tell if manufacturers can produce a backspin barrel that will still be accurate.  We will leave ball spin for another article.  So other than ball spin, what other factors are there?

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What affects the range of a paintball?

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First some basics about Newton's Law. Newton’s First Law states a couple very important things:

1. An object at rest will remain at rest unless some unbalanced force causes it to do otherwise.
   There is this funny little thing in physics class that you might remember from high school called Newton’s First Law.  Newton’s First Law is also called the law of INERTIA. Inertia is basically the force that it takes to move an object, and momentum is the force that the object carries with it as it is moving.   You could also think of momentum as the force required to slow an object down as it travels.    You will see how this applies to the range of a paintball in a second.  I am not a physics major but I am trying to make a simple point.
2. An object in motion will continue in motion in a straight line with constant VELOCITY unless some unbalanced force causes it to do otherwise.
   If there were no wind resistance or gravity (as in outer space), an object would continue on a straight path with virtually unchanging velocity.

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Newton’s Second Law says: F=MA or (force equals mass times acceleration)

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So INERTIA is equal to MASS x VELOCITY.

Now lets apply these laws to paintball. If you take a golf ball and a ping pong ball that are the exact same size, and you throw them one at a time as hard as you could, which would go further?

Obviously the golf ball would go further. Since it has more MASS than the ping pong ball, it takes more FORCE (due to its higher inertia) to throw it. This means it has more MOMENTUM than the ping pong ball. If two objects are going the same VELOCITY (300 fps), but one is heavier than the other, which one will go further? The one with more momentum. The ping pong ball and the golf ball may leave your hand at the same VELOCITY, but the ping pong ball will be decelerated by the air much more quickly than the golf ball. The golf ball also take a lot more FORCE to go the same velocity as the ping pong ball when it leaves your hand. To sum it up, there are only two things that will determine how much momentum the paintball has when it leaves the barrel.

• Velocity of the ball
• Weight of the ball

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Trajectory (arc of the ball's flight)

Some people argue: "my gun has a flatter trajectory than gun A".  This is another one of the great misunderstanding among paintball players.  There is no such thing as one gun having a different trajectory over another without ball spin.  The proof to my argument rests again with Newton's Laws of physics.   This application of physics is called "projectile motion".   Basically, the factors that control trajectory are gravity, mass, velocity, and angle of the projectile as it leaves the gun.  A projectile shot at 45 degrees will travel the greatest distance possible.  An angle greater than 45 degrees will cause the ball to go
higher, but it will hit the ground closer to its starting point.   A projectile shot at less than 45 degrees will hit the ground faster due to acceleration of gravity, causing it to not travel as far. Gravity is a constant, and the acceleration due to gravity (32.2 ft/s/s) is the same for all projectiles no matter what their weight. We are assuming for this article that the aerodynamics is the same for all paintballs.

A ball of heavier mass will go farther, remember?  So weight of the ball once again plays a part in the flight of the ball, controlling how high and how far the ball will go.

Now lets talk about other factors that affect VELOCITY, since the weight of the ball will not change very much, but the velocity from shot to shot can vary greatly.

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Barrel length affects velocity fluctuations

The way that a ball bounces around the barrel or drags against the inside of the barrel can have a profound effect on velocity fluctuations. Balsl will touch the sides unevenly sometimes and drag will slow the ball down. The longer the barrel is, the more pronounced these fluctuations can be. For this reason, a shorter barrel will have less velocity fluctuation than a longer one. Balls that are out of round will also vary in velocity both because they drag differently in the barrel, and because they have unequal air resistance as they fly. An oversized barrel can compensate for this, but that also introduces other factors that can vary your velocity.

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Air density.

The barometric pressure changes constantly. As an exaggerated example, is it easy to run through water? Of course not. The weight of the water makes it harder to move through than air does. Slight variations in air density and humidity can have the same effect.

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What do vented (drilled) barrels do?

Barrels with holes in them do not affect the range of the paintball. Tom Kaye (owner of Airgun Designs) hired the people from Kodak to come out to his factory and shoot some high speed film of paintball guns firing to see what happens when the ball comes out of the barrel, etc. In one test, they had a stream of smoke right at the end of the barrel. The barrel was SOLID and clear. When the ball emerged from the barrel, there was no "puff" of air that hit the smoke ahead of the ball. The only thing that hit the smoke was the ball. This debunks manufacturer claims that the holes in their barrels reduce air pressure in front of the ball.

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Vented Barrels Continued

Another theory by makers of drilled barrels is that the holes somehow equalize pressure in front and behind the ball, making the ball regain shape as it goes down the barrel. The claim is that the ball is more round making it travel farther in the air. What the holes actually do is release the pressure behind the ball, causing it to stop accelerating. They also make the gun quieter.  That is all they do.

Airgun Designs used computers to measure the acceleration and power pulse behind paintballs as they travel down the barrel. What they found is that in most paintball guns the ball accelerates in the FIRST 8-10 INCHES OF THE BARREL ONLY. This means that if a barrel is any longer than say 12", it is only slowing the ball down in the barrel. Barrels that are drilled usually only have about 6" of solid barrel.  This means their EFFECTIVE LENGTH is only six inches. Shorter barrels have less distance to accelerate in, so the ball sees more force to go 300fps.  Once the ball goes past the holes, the air pressure behind the ball is GONE.  The ball immediately stops accelerating.

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Wobbling Paintballs?

Another popular theory is that the ball "wobbles" through the air like a water balloon. I have even read and heard people say that the front and back of paintballs are almost flat as they travel down the barrel. This is just not true. The slow motion pictures from AGD show the ball travelling down and out the end of the barrel and guess what? They are PERFECTLY ROUND.   When the air pushes the ball down the barrel, the air CONFORMS to the shape of the ball, actually "cupping" the ball. This is because the pressure behind the ball is distributed evenly. If the air were to accelerate the ball like a piston, the balls would break, because a typical paintball sees around 3,000 Gs. That’s a tremendous force, but the ball can handle it because the PSI on the ball surface is only around 100psi.

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Negating backspin-inducing bent barrles, the answer is none.  What I mean by this is that there is not ONE gun that can out-range all others because if its regulator, valve pressure, air chamber , etc.

If you hear someone say "man that guy's gun really out-ranged me",then you know that this is usually not true.  The human perception of the balls coming at you makes it appear that the opponent has greater range than you.   This may be true, but only if his velocity is higher than yours and his paintballs are heavier.  That's it.    Most players cannot see their paintballs in the air after they travel a certain distance. Usually it is impossible to follow the ball all the way to the target.   If the other player is not ducking for cover as you are shooting at him, it may be because he is less afraid of getting hit than you gave him credit for.   To you, it looks like your balls aren't reaching him, but in fact they may be, but he just has a lot of nerve.  Another thing to remember is that better players will hang out longer in a long-ball exchange like this.   You may give up on hitting him because he is not flinching, but he knows that the best chance he has of hitting you is when you are out of your bunker shooting.  Suddenly he hits you, and you say "man that guy out-ranged me".  This is a tough lesson to take for most people, because they expect other players to duck when they shoot at them.   Knowing this bit of psychology will help you to defeat long ball opponents.

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Barrel choice usually does not affect accuracy

A paintball does not care what barrel it came from or how slippery the inside of the barrel was after it has left the gun. Accuracy is affected mainly by what happens to the ball AFTER IT HAS LEFT THE GUN.  If the ball has paint on it or is dirty, the paint will alter the flight of the ball due to irregularities in the flow of air  over the surface of the ball. If wind pushes on the ball, it forces it off course and it won’t go where you  thought it would.  If the seam is not formed well, or the ball is out of round, the air will not flow evenly over the ball and it will go off course. 

Here is a list of possibly factors (in no particular order) that will affect your accuracy:

• Velocity too high ( over 280 can cause curving)
• Paint in the barrel
• Dirt in the barrel
• Oil in the barrel (after lubing gun)
• Dirty paintballs
• Out of round paintballs
• Cracked paintball
• Uneven fill mixture (old paint)
• Dimpled paintballs
• Wind
• Humidity
• Barrel bore too tight
• Bent barrel

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Ball spin does not affect accuracy?

The problem with spinning a paintball is that it is not solid like a lead bullet. You can get the shell of a paintball to spin, but the fill may not spin in sync. Ever spin a glass of water that has ice in it?  The ice stays in one place. The fill of the paintball acts the same way, and after the ball leaves the barrel, the ball quickly stops spinning.  Tom Kaye suggests that spin in not a factor below 3,000 rpm.  I'm not sure I agree with him, but it is important to note that balls that curve badly after going through a dirty barrel do do because the paint/dirt that is on the ball does not allow the air to flow evenly over teh surface of the ball.    Aerodynamics of a round ball are not so great because of the turbulence behind the ball, and when you shoot a ball through a dirty barrel it only makes things worse.  Any variation in the shape of the ball will make it go off course.  Many players assume that a dirty barrel causes a ball to spin, which makes it curve.  The paint residue on the surface fo the ball has a more profound effect on the curve of the ball.

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Turbulence affects the accuracy more than any other factor

There is a reason why the army does not shoot musket balls anymore. They aren’t accurate. The shape of a sphere going through the air causes turbulence behind the ball that can send it off course very easily. So basically the way that the air travels over the ball will affect it’s flight.  Combine that with a paintballs low weight, and you get a projectile that is ill suited for long distance accuracy, and is easily thrown off course.  Perhaps this is why so many players are obsessed with the "perceived" accuracy performance of their guns.

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The worlds most accurate barrel

Hate to disappoint you, but there is no such thing.  What you want to look for in a barrel is one that loads the ball gently, has an effective length of 8-12 inches, doesn't double feed, and has a bore that best matches the balls you are using.   When I get mail asking "what do you think of barrel XYZ", I just laugh.  There is no one barrel that is the best.  If you play in competitions or travel from field to field, you are going to be forced at one time or another to use field paint.    You cannot guarantee the balls are round, or that the fill is mixed evenly, or that the shell is not dimpled, or that the size of the ball will match you one "favorite" barrel.   My advice on barrel selection is to get a few barrels that seem to perform well with the paint brand and color that you use most often.   Having barrels of varying inside diameters will come in handy when the tournament paint doesn't work in your favorite barrel.

Hate to disappoint you, AGAIN, but there is no such thing.  EVERY brand of paintball has good and bad batches. They vary slightly in size, weight, and shape.  The best way to test a paintball is to drop them from about 4 feet high onto a concrete floor.  If more than one or two breaks out of 20, then the shell is too brittle.   You can fix this if you are stuck with brittle tourney paint by placing an open glass of water inside the case bag and sealing it up.  Leave it for a couple of hours.  This basically humidifies the balls and makes them more resilient. Ever seen a wet paintball after a rain? Well this isn't nearly quite that extreme, but you get the idea. The balls will break less in the gun.

They can, but paintballs are not always round.  Spin, weight and shape of the ball.  Use heavier balls and they should go straighter, further, and they should hit the target harder.

Usually the thicker the fill, the heavier the ball. Waxy filled balls are slightly heavier than other balls.An RP Scherer rep told me that their "gold" series paint has a nasty thick fill and is a heavy ball.  That’s what you want to look for.  RP Scherer Premium Gold would be my choice.

Now you know the truth.  The answer is none.  There is not one barrel that will work the best with ALL paintball brands, ALL paintball guns, and ALL paintball colors, in ALL types of weather.  There are just too many variables for one to be the best.

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