effect bullet velocity?
By TJ F.
TJ F and display
TJ F and display
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The purpose of
this experiment is to see how changing the bullet weight and powder amount
and type. My hypothesis is that the maximum powder amount with the
Imr-4350 and the 60grain bullet will produce the fastest combination.
The constants of this experiment are all of the reloading and shooting
equipment and the testing supplies. The manipulated variables of
this experiment are the powder amounts and types and the bullet weight.
A chronograph will measure the speed at which the bullet travels.
In the end it
turned out that the Imr-3031 with maximum powder and a 60grain bullet had
the fastest speed. My hypothesis was correct for the exception of
the powder type. If some one were to complete this project again
I would recommend that they test a wider variety of bullets and powders.
The purpose of this experiment is to find out how changing the powder amount and type and bullet weight affects the velocity of the bullet. The results of this experiment will hopefully answer many hunters’ and marksmen’s questions about what cartridge they should use for their particular shooting needs. This problem was selected because of a personal interest in the field of shooting. I have been hunting since the third grade so I have always been fascinated with how the cartridge you are using can affect whether your hunt is successful or a failure.
I will be testing three different powders (Imr-3031, Imr-4350, and h-4831), three different amounts, and three different bullet weights (60grain, 75grain, and 100grian). I believe that using the Imr-4350 and the maximum amount of powder with the 60grain bullet will achieve the highest velocity. I base my hypothesis from an article read in the Nosler reloading guide by Tom Gresham editor of Sports Afield magazine.
The constants in this project were:
o Reloading apparatus
In this Project
the powder amount and type were changed along with the bullet weight.
All of the powder amounts were divided by “small, medium, and large”.
There is no set increment at which the powder increases, but what is usually
used. For exact measurements for each the powder amount for each
cartridge refer to the results section. The three powder types that
were used were Imr-3031, Imr-4350, and H-4831. The numbers in the
title of each powder do not represent the amount of power put out when
burnt. All they are are ways of identifying them. And the three
bullet weights were 60grain, 75grain, and 100grain. Again there is
not a specific increment that the weights are increased by, but a “small,
medium, and large” system. The responding variable of this project
will be the velocity of the bullet. To measure this a chronograph
is used. All measurements produced by the chronograph will be in
feet per second so conversions will need to be made.
Since all reloading is preformed with standard measurements everything will be expressed in both standard and metric.
Safety glasses
Hearing protection (ear plugs or
a head set)
RCBS single stage loading press
RCBS .243 shell holder
RCBS .243 reloading dies
RCBS model 5.0.5 reloading scale
RCBS powder trickler
Pacific Tool Company case sizing
lubricant and pad
Chicago Brand Caliper
27 CCI large rifle primers
27 empty Remington cases
1 can of Imr-3031 smokeless powder
1 can of Imr-4350 smokeless powder
1 can of H-4831 smokeless powder
9 Sierra Varminter 60 grain bullets
9 Hornady 75 grain bullets
9 Remington 100 grain bullets
Chronograph
Ruger .243 rifle
Shooting bench
-Assembly Procedures-
Before attempting to hand load a cartridge, read a reloading manual that can easily be understood and or have some who has experience in the area. Check reference section for possibly readings. It is critical that during hand loading you are using extreme caution. During powder pouring and bullet seating wear safety glasses.
1. Begin by cleaning and inspecting
the cases for any imperfections.
2. Once the cases have proven to
be flawless, lubricate them with the sizing lubricant. Be sure not
to over-lubricate for any excess lubricant on the case will cause dents
in the case during the resizing process.
3. Re-size the over-all length
of the cases by placing them in the loading press with the #1 die.
4. Remove old primer by using the
#1 die in the press.
5. Clean the lubricant from the
casing with a clean piece of cloth.
6. Using the deburring tools remove
any burrs from the inside and outside of the case.
7. Fully extend the arm of the
press and place the case in the holder. Then fit a rifle primer into
the primer arm and hold the arm in place under the case. Pull the
lever down to seat a new primer in the case.
8. Repeat steps 1-7 enough times
to have 27 ready cases.
9. Calibrate the balance.
10. Now according to the table
below fill each case with the powders and amounts listed. Assume
each cell of the table represents a separate case.
11. According to the table above
seat the bullet by using the #2 die. Fit the case in the shell holder.
With your hand hold the bullet above the neck of the case. Slowly
push the case up seating the bullet as you remove you’re the hand that
is holding the bullet in place.
12. Check that the cases are the
appropriate length with the caliper. For the 60grain bullets the
cartridge over all length (or Col) should be 2.67 inches (6.78cm).
For the 75grain and 100grain bullets keep the Col at 2.71 inches (6.88cm).
It is important to have the appropriate Col because 1) if it is not the
right length it may not chamber correctly and 2) when it is chambered the
closer the bullet is to the rifling the more accurate the shot will be.
13. Wipe the fully loaded cartridge
with dry rag.
14. Label and set aside.
15.Now that all of the cartridges
have been loaded properly continue on to the Testing Procedures.
-Testing Procedures-
Selecting the location in which you are testing is very important. Unless you have a field with a safe backdrop (no houses, animals, etc.) it is recommended that you go to a shooting range to perform the testing.
1. Assemble a stand for the chronograph.
2. About 8 feet (2.5 meters) away
from the chronograph assemble a shooting bench or any sturdy surface that
you can make accurate shots from.
3. Place the rifle on the shooting
bench.
4. Note: Again, remember to be
shooting in a safe direction!
5. After hearing protection is
in place allow designated shooter to shoot the first round through the
chronograph. Make sure you know which round was fired.
6. Record the feet per second that
the bullet traveled from the chronograph’s read-out.
7. Repeat steps 5-6 until all 27
rounds have been fired and the feet per second have been recorded.
8. Now that all of the measurements
have been taken began converting all of the feet per second measurements
to meters per second.
-Introduction-
With this project the knowledge of
rifle ballistics will hopefully be furthered. The information gathered
could help any one who enjoys target practicing or hunting. The science
of reloading is very precise and small changes can greatly affect the outcome
of any test.
-Ballistics-
Ballistics is a broad term used to
describe several parts of the projectile’s path. Interior ballistics is
when the projectile is in motion through the barrel of the rifle.
Any one that studies internal ballistics studies how forces affect the
projectile such as is still in the barrel of the rifle. The speed
in which the bullet leaves the barrel is initial velocity. Exterior
ballistics deals with the behavior of a projectile from the time it leaves
the weapon until it ends its flight. To determine the trajectory
you must know the initial and the effects of gravity and air on the projectile.
Since gravity pulls the projectile to the ground and the air slows its,
it is difficult to calculate exterior ballistics. Air affects the
range along with the projectile’s size, shape, and weight. To increase
procession placing a spin on a projectile creates gyroscopic procession.
When the object is spinning cross winds have a smaller effect on the projectile.
Terminal ballistics is the study of the effects of a projectile’s impact
on the target. Since target come in any size and shape the study
of materials and structural science. Damage to a target can be from
fragmentation, impact, blast, and heat. Size and shape are large
factors.
-Velocity-
Uniform velocity is when the distance and speed remain
constant throughout the projectile’s travel.
V=D/T
V= velocity
D= distance
T= time
Variable velocity is when the distance traveled in a given unit of time is not equal throughout time of travel. Or in other words the velocity will change throughout the projectile’s flight.
V1-V2
2
V1= initial velocity
V2= ending velocity
-Propellant-
In order for the bullet to move anywhere
a propellant needs to be present. When the pin hits the primer and
ignites the propellant a high-pressure gas is formed inside of the cartridge
and forces the bullet out of the barrel. Your classic Black Powder
Rifle uses black powder for the propellant. Black powder is made
of three components: saltpeter (potassium nitrate), charcoal, and sulfur.
These ingredients are compressed then broken up into small granules to
make black powder. Modern firearms use smokeless gunpowder.
Smokeless gunpowder contains nitrocellulose and nitrate salts. There
are many sub-categories for these powders, but most are not used because
of cost.
-The Rifle-
A rifle is a gun with spiraled grooves
inside the barrel that spin the bullet as it leaves the barrel, giving
it gyroscopic precession, which is more accurate. When a bullet is
spinning the forces of nature have a smaller effect on the bullet’s movement.
All rifles have four basic parts to them. They are the action, barrel,
stock, and the sites. The action is the mechanism that is found at
the middle of the gun. This part of the gun is responsible for loading,
firing, and ejecting the cartridge. There are many different types
of actions such as the lever action, bolt action, and break action.
The barrel is a steel tube spiraled grooves on the inside that are called
rifling. The far end of the barrel is called the muzzle and the end
near the action is called the breech. The barrel is the part that
the bullet actually travels through. The stock of a rifle is traditionally
all of the woodwork on the rifle, but on newer rifles synthetic stocks
are used for a lighter gun. The part of the sock that covers part
of the barrel is called the fore grip and the part near your shoulder is
the butt. One of the most important parts of the rifle is the sites.
The sites are usually two metal pieces that sit on the barrel, near the
breach and the other at the muzzle. The rear site is usually a fork
shape and the front is just a single post that is used to line up with
the rear site. Some rifles do not use iron sites, but scopes.
Now a scope is a durable tube with glass lenses. The lenses are curved
to magnify the target.
In the end of this project many new and interesting things were discovered. As you can see Imr-3031 produced the fasted speeds, the Imr-4350 had the second fastest, and the H-4831 coming in at third place. The 60grain bullet was the lightest and as the bullets got heavier the speeds progressively become slower. Of course the more powder in the cartridge the faster the bullet went. So in the end the fastest combination was 41grains of the Imr-3031 with a 60grain bullet. There were not many unusual things about the results, as one might expect the more powder and the lighter the bullet the faster it went. In a way the only question answered with this project was what type of powder created the most gas when burnt.
Like mentioned
in the results section it is somewhat predictable that the lighter bullet
with more powder would have faster results. In my original hypothesis
I said that a maximum load of the Imr-4350 with a 60grain bullet would
produce the fastest speed. So I was correct about the bullet weight
and powder amount, but incorrect about the powder type. This comes
to me as a slight surprise because I based the portion of my hypothesis
that related to powder type on more than one article.
Possible sources
of error for this experiment could have been the age of the powders I used.
The Imr-3031 was not any older than a few months while the Imr-4350 was
over a year and the H-4831 was over 10 years old. The reloading process
was done within a fairly short time period to keep the temperature of the
air inside the cartridges the same. But any difference in the air
temperature could have caused the air to expand or contract in the case
throwing the results. Another possible source of error could have
been the chronograph. Since it uses motion sensors to detect
the bullet direct sunlight could have affected the response. Plus
the battery life of the chronograph could have affected the accuracy of
the readout.
If someone were
to perform this project again I would recommend trying to find a way to
test the impact, or foot-pounds of pressure, of the bullet. Another
thing I would recommend would be to test it several times; due to shortness
of funds only one round of testing could be completed. It would also
be interesting to see how different guns of the same caliber performed
in comparison to each other.
Ackley, P.O. Handbook for Shooters and Reloaders. Utah: Plaza Publishing, 1962.
Garmon, Lucille. “Velocity.” The World Book. 1999 ed.
Gresham, Tom. Nosler Reloading Guide. Oregon: Chevalier Advertising, Inc, 1996.
Kennedy, James. “Gunpowder.” The World Book. 1999 ed.
Lussier, Frances. “Rifle.” The World Book. 1999 ed.
Temperley, Judith. “Ballistics.”
The World Book. 1999 ed.