Paintball: Myths vs. Physics
Upon reading the many product reviews and field stories of paintball, I
realized that the sport is filled with several myths. Some of these myths
are born of people who hold a particular fondness of one gun over another,
and often these myths work to the advantage of companies who are trying
increase their foothold in the market. It's surprising just how powerful
the bandwagon effect is in the sport of paintball.
Many of these myths can be dispersed with a basic knowledge of physics, or
at least with a good dose of common sense. I used to major in engineering
and hold a minor in mathematics, and would like to give my two cents on a
few topics in hopes that it will help a few consumers out there.
The distance a paintball is shot depends mostly on two things: 1) the
horizontal velocity of the ball, usually measured in feet/second, and 2)
the time it spends in the air, usually measured in seconds. Just multiply
the two measurements together; the seconds cancel out, and you're left
with some number measured in feet. Simple physics.
Assuming your marker is aimed perfectly flat and the air is still, the air
time and velocity are determined by the time it takes for the ball to drop
to the ground from barrel height and the average velocity of the ball. (I
say average velocity, not muzzle velocity, because the ball slows due to
air resistance.) Then, variations in range come mostly from dips and
peaks in 'gun pressure (affecting speed), and deformities in paintball
shape (affecting average speed by changing air resistance). Range can
also vary wildly by simply tilting the 'gun up and down; tilting up
increases the air time by increasing the maximum height of the ball, but
decreases horizontal velocity since some of it is transferred upwards.
Optimal tilt for maximum range is around 45 degrees.
What does this mean? It means that maximum range can only be increased by
chronoing in faster, or by somehow increasing airtime by slowing the
ball's drop to the ground. This is where products like the Flatline or
Z-Body come in; both create backspin on the ball, generating lift. The
extra range may or may not be worth it since at long range, air resistance
takes such a toll on speed that the ball may lack the momentum to break.
I believe that benefits of these products lie more in ease of aiming;
arcing is flatter since the paintballs fall at a slower rate. And no,
closed-bolt 'guns don't shoot flatter than open-bolt. Once the ball
leaves the barrel, it's subject to the same laws of physics as with other
'guns. And since air resistance has the same affect on all paintballs,
funny riffling or porting doesn't cause a ball to "hit harder" than with a
regular barrel when they're cronoed the same.
There are several methods of achieving good accuracy. The tried & true
method is to use the straightest, smoothest barrel possible along with
some good fitting quality ammo. Burrs, rough spots, joints, badly cut
porting, or slight dents will catch, causing the ball to veer one way or
the other. A good fit is just as important: if the barrel is too big, the
ball will actually bounce back and forth as it moves through the barrel,
exiting in who-knows-what direction. Too small, and imperfections in the
ball may rub unevenly against the sides, affecting the exit path or
Another method is to copy firearm ballistics by giving the paintballs a
gyroscopic spin. The way this provides stability is by indirectly
counteracting outside forces and by balancing out imperfections in weight
distribution. Picture a household toy gyroscope: If you add some weight
to one side of the spinning wheel, the toy should spin as it did before
without noticeable wobble. The weight is sort of averaged out with the
spin, at least at high speeds. Place that same weight on a side of the
gyroscope cage that doesn't spin, and gravity will start to pull that side
downwards. But since gyroscopes counteract forces at right angles, the
toy will slowly start to turn sideways, seemingly defying gravity even
though it is tilted slightly.
The idea is to get these same features in a paintball, albeit at lower
speeds. The first attempt by manufacturers was to rifle barrels similar
to those of firearms', with grooves twisting one way or the other down the
length of the barrel. The payoff of these barrels is arguable. The
effect isn't that great, they need well fitting paint to work, and tend
not to work well after a ball break. On the other hand, the Flatline's
design seems to work well, though I've never heard how well it performs
after a break. (How do you squeegee them out, anyway?) BTW, don't
believe that heavy spiral "rifle" porting helps with accuracy; it has no
way of forcing spin on a paintball, and may provide another surface for
the paintball to catch on.
Multi-stage barrels are a mixed bag. I have doubts about any design that
has sudden shifts between calibers, and have yet to hear an argument on
how they're expected to work. But I've heard good things about barrels
with smooth diameter changes like the one made by Palmer.
Closed vs. open bolt accuracy arguments sound inconclusive. The military
seems to think that open bolt firearms are less accurate, which is why
they don't use guns like the Uzi. However, controlled tests with
paintguns haven't revealed tighter shot groupings with closed bolt 'guns.
Believe what you want.
My advice on achieving accuracy: Get a nice barrel/paint combo, use a
regulated air source to get consistent range, aim (with a sight!), and
PRACTICE. Get used to your marker, and take it to a target range. Don't
think that the latest whiz-bang barrel will make that much of a
There are four 'gun features that have a great affect on efficiency. In
no particular order, these are paint/barrel fit, unported barrel length,
'gun valve design, and operating pressure. I'm sure you've heard barrel
fit explained... too large, and air blasts around the paintball; to small,
and more air is needed to force the ball out.
Unported barrel length is important as well; the reason we have barrels is
to provide an area for the air pressure to push the paintball. The ball
accelerates while in the barrel, and immediately begins to slow down once
it exits. This is why longer barrels are generally more efficient, unless
they're full of holes. Excessive porting is good for quieting a 'gun, but
lets the air leak out of the barrel when it should be pushing out the
Valve design has an effect on gas consumption as well. Open bolt 'guns
use or store air pressure to recock the hammer, while automated closed
bolt 'guns use air to operate the cocking mechanism. Open bolt designs
also lose air up the elbow with every shot, as can automated closed-bolt
designs if they're not timed correctly. Theoretically, pump 'guns are the
most efficient, since they are closed bolt and are cocked manually.
Double action paintguns would be very efficient as well, if they existed.
Whatever the design, 'guns are more efficient when they've been optimized
for a certain operating pressure.
A lot of people seem to think that low pressure = high efficiency. One of
the arguments is that your tank can be emptier and still provide the
pressure necessary to operate the 'gun, but this doesn't deal with
shot-by-shot gas consumption. As far as the paintball is concerned, it
needs to absorb a very certain amount of energy to make it up to 300 fps.
This can be done by blasting it with a small volume of high-pressure air,
or a larger volume of low-pressure air. A larger volume is required
because low-pressure air is inherently less energetic, and larger volume =
more air used per shot.
It's not that running at low pressure has no advantages. It seems to be
quieter; it's more gentle on the ball, causing less breaks; it also allows
the use of higher quality, thin skinned paint that breaks more easily on
impact. But low pressure is something to avoid if every shot counts, like
during stock class play.
Low-pressure chambers may or may not help with efficiency. They do
provide a reservoir of pre-depressurized air for the valve to use, but
that air still has to come from the air tank. They *might* be useful at
decreasing gas usage between shots, more so with CO2 based 'guns since it
takes them longer to recharge between shots.
I didn't write all this to bash on or endorse any products. I wrote it
because of things I heard that didn't agree with all those physics classes
I took, or things that defied common sense. I'm not an airsmith, so if
there are holes in my reasoning or if things just don't make sense, email
me at firstname.lastname@example.org