Tweet
First let me set some basis for ballistics...
Lets take a look at ballistics from a simple empirical point of view:
-A bullet is an object.
-If one shoots an object in the air all objects are subjected to the same laws of physics no matter what they are.
- The longer an object stays in the air the longer the object is exposed to the forces that have an influence in its trajectory.
- By the same token, when one is trying to hit an objective with an object, the fastest one can get to the objective, the less
time that object is exposed to those forces and variables so initially we could say it is easier to predict their trajectory/behavior.
- The time an object stays in the air can be influenced by changing the following variables:
A) The distance to the objective.
B) The initial launching speed of the object we are using to hit the objective.
C) The environment conditions such the air pressure and temperature.
D) The shape and construction of that object so one can predict how well that object cuts through the air.
All these rules of physics apply to bullets as much as they would apply to an old canon ball. All bullets are subjective to the same rules that
are 100% supported by mathematics. Some simple mathematics, some more complex.
speed = space / time.
For example:
2000 fps = 2000 ft / 1 second
This bullet has the potential to cover 2000ft in one second but this is not going to happen because a bullet doesn't have an engine
to maintain that speed constant so it will decelerate to a degree. But for now lets leave that aside.
By the understanding of this simple formula if we increase distance (space) w/o increasing the speed then the time will increase.
Time = space / speed.
1 second = 2000 ft / 2000 fps.
So if we increase the distance to 4000ft ...
Time = 4000ft / 2000fps = 2 seconds.
If we keep increasing the distance the time will increase if we do not do anything else. As the time increases the bullets are
subjective to several forces like gravity (that is constant for all objects) and wind, temperature, etc...
So the longer we stay in flight the more corrections we need to apply to make sure we hit those targets.
Based on the above one could poentially have the trajectory unaffected by increasing the speed lets say to 4000ft/s.
So that will give us 4000ft / 4000ft/s = 1second.
I am using these numbers oversimplifying things and for the purpose of the explanation but so one clearly see that it is very important
to any serious long distance shooter to start with a decent speed and possibly use bullets that will not be impacted so much by wind
and drag in the air. Because bullet with flat points or small bullet lengths for the given caliber are going to be decelerating faster and
therefore take longer and therefore be exposed to the gravity and wind longer.
One could actually start slower with a tad slower bullet that is a good flyer and cover the distance in less time that is also an important
consideration for long distance shooting since one can only increase the speed so much in the same case w/o running into high and
dangerous combustion pressures.
So, w/o getting too technical how this all applies to the real world?
Well it really depends on what one is expecting to do from the rifle caliber in question. If one is going to shoot short distances a slower
or less efficient bullet might do.
Also needs to consider not just the caliber and energy but the speed at impact for the proper function of the bullet. If you are shooting
steel rams with the TC pistol you can choose heavy bullets and forget about the speed because all you want is momentum at time
one hits the steel so one can know it down.
But military and tactical people are looking for the speed with good bullets. Both to ensue that the trajectories can be more easily predicted
and that when the bullets get to the targets they have enough speed to take maximum advantage of the characteristics of their terminal design.
Weight is also an important trade off so a lighter bullet with lots of speed might be favored vs. heavier bullets too slow and heavy for the caliber.
This is why you saw the Russians follow the western directives and displaced the 7.62x39 with the lighter and faster 5.45. one could argue a caliber in 6mm, 6.5mm or 6.8mm would be a much better choice but the armies will never ever adopt again a slow moving 30 caliber like the 30 carbine, 7.62x39, whisper/blackout/ 7.62x40 or anything similar. On that caliber and for any decent performance in terms of speed and trajectory the 308w/.7.62x51 NATO does very well, including long distance shooting with 175gr bullets that provide decent trajectories and lots of momentum
on the target.
Also keep in mind that in order to defeat certain hard barriers and materials one needs speed. If you also look at the most efficient and popular
hunting bullets the minimum speed threshold recommended by manufactures for maximum expansion and efficiency is on the 1600fps to 1800fps.
So that is why it is in the best interest to the shooter for many objectives and applications to consider a round with some decent speeds
and somewhat flat trajectories. the most accurate calibers are round in this category and with extensive usage of intermediate calibers
for all purposes.
Obviously if one is going to Africa on a hunt large game one will need not only some decent speeds but lots of grain and solid bullets to assure quick dispatching of some very hard to kill animals. But here ranges are short so there is no concern for trajectories and everything is bet on
terminal performance.
Lets take a look at ballistics from a simple empirical point of view:
-A bullet is an object.
-If one shoots an object in the air all objects are subjected to the same laws of physics no matter what they are.
- The longer an object stays in the air the longer the object is exposed to the forces that have an influence in its trajectory.
- By the same token, when one is trying to hit an objective with an object, the fastest one can get to the objective, the less
time that object is exposed to those forces and variables so initially we could say it is easier to predict their trajectory/behavior.
- The time an object stays in the air can be influenced by changing the following variables:
A) The distance to the objective.
B) The initial launching speed of the object we are using to hit the objective.
C) The environment conditions such the air pressure and temperature.
D) The shape and construction of that object so one can predict how well that object cuts through the air.
All these rules of physics apply to bullets as much as they would apply to an old canon ball. All bullets are subjective to the same rules that
are 100% supported by mathematics. Some simple mathematics, some more complex.
speed = space / time.
For example:
2000 fps = 2000 ft / 1 second
This bullet has the potential to cover 2000ft in one second but this is not going to happen because a bullet doesn't have an engine
to maintain that speed constant so it will decelerate to a degree. But for now lets leave that aside.
By the understanding of this simple formula if we increase distance (space) w/o increasing the speed then the time will increase.
Time = space / speed.
1 second = 2000 ft / 2000 fps.
So if we increase the distance to 4000ft ...
Time = 4000ft / 2000fps = 2 seconds.
If we keep increasing the distance the time will increase if we do not do anything else. As the time increases the bullets are
subjective to several forces like gravity (that is constant for all objects) and wind, temperature, etc...
So the longer we stay in flight the more corrections we need to apply to make sure we hit those targets.
Based on the above one could poentially have the trajectory unaffected by increasing the speed lets say to 4000ft/s.
So that will give us 4000ft / 4000ft/s = 1second.
I am using these numbers oversimplifying things and for the purpose of the explanation but so one clearly see that it is very important
to any serious long distance shooter to start with a decent speed and possibly use bullets that will not be impacted so much by wind
and drag in the air. Because bullet with flat points or small bullet lengths for the given caliber are going to be decelerating faster and
therefore take longer and therefore be exposed to the gravity and wind longer.
One could actually start slower with a tad slower bullet that is a good flyer and cover the distance in less time that is also an important
consideration for long distance shooting since one can only increase the speed so much in the same case w/o running into high and
dangerous combustion pressures.
So, w/o getting too technical how this all applies to the real world?
Well it really depends on what one is expecting to do from the rifle caliber in question. If one is going to shoot short distances a slower
or less efficient bullet might do.
Also needs to consider not just the caliber and energy but the speed at impact for the proper function of the bullet. If you are shooting
steel rams with the TC pistol you can choose heavy bullets and forget about the speed because all you want is momentum at time
one hits the steel so one can know it down.
But military and tactical people are looking for the speed with good bullets. Both to ensue that the trajectories can be more easily predicted
and that when the bullets get to the targets they have enough speed to take maximum advantage of the characteristics of their terminal design.
Weight is also an important trade off so a lighter bullet with lots of speed might be favored vs. heavier bullets too slow and heavy for the caliber.
This is why you saw the Russians follow the western directives and displaced the 7.62x39 with the lighter and faster 5.45. one could argue a caliber in 6mm, 6.5mm or 6.8mm would be a much better choice but the armies will never ever adopt again a slow moving 30 caliber like the 30 carbine, 7.62x39, whisper/blackout/ 7.62x40 or anything similar. On that caliber and for any decent performance in terms of speed and trajectory the 308w/.7.62x51 NATO does very well, including long distance shooting with 175gr bullets that provide decent trajectories and lots of momentum
on the target.
Also keep in mind that in order to defeat certain hard barriers and materials one needs speed. If you also look at the most efficient and popular
hunting bullets the minimum speed threshold recommended by manufactures for maximum expansion and efficiency is on the 1600fps to 1800fps.
So that is why it is in the best interest to the shooter for many objectives and applications to consider a round with some decent speeds
and somewhat flat trajectories. the most accurate calibers are round in this category and with extensive usage of intermediate calibers
for all purposes.
Obviously if one is going to Africa on a hunt large game one will need not only some decent speeds but lots of grain and solid bullets to assure quick dispatching of some very hard to kill animals. But here ranges are short so there is no concern for trajectories and everything is bet on
terminal performance.
Comment