what cals are flat ?
- Thread starter AKD
- Start date
not asking cus im buying just curious. One of my guns is a 22-250 and a friend has a 270. I always find it impressive how flat there trajectory is.
it got me wondering, what round seams to drop the least ...... lets say out to 500m
it got me wondering, what round seams to drop the least ...... lets say out to 500m
No it isn't. Galileo disproved that on the leaning tower of Pizza
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No it isn't. Galileo disproved that on the leaning tower of Pizza
In a vacuum, all objects are accelerated equally toward the earth by gravity. However, the value of ballistic coefficient is directly proportional to the sectional density and thus weight of a bullet. Weight is therefore one of the factors affecting trajectory through the earth's atmosphere.
http://en.wikipedia.org/wiki/Ballistic_coefficient
The original poster's question is too subjective. How does one define a flat trajectory or what constitutes high kinetic energy? If you want to compare trajectories and kinetic energy for different cartridges, have a look at any of the ammunition manufacturers tables or use a ballistics calculator like this:
http://www.realguns.com/calc/exteriorballistics
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- Virden, MB
Flat and fast are fine, but accurate is more important. As long as your scope can track then more clicks when dialing is no big deal really. In the hunting world flatter is great cuz you can sight in 1 1/2" high at 100 and with a slight holdover be good for 300.
Personally I like the 7mm better than 30 cals just for that, but really the question is too subjective.
Personally I like the 7mm better than 30 cals just for that, but really the question is too subjective.
Edit: I get it now. You know that after 1 second flight time, all bullets drop the same distance. By drop you mean the distance moved downwards per 100 yards of forward motion. So I see drop as the distance dropped, you see it as a ratio. Distance dropped has nothing to do with mass, but forward velocity is indirectly influenced by mass, yes.
Two bullets of different weight can have the same BC.
Two bullets of different BC can have the same weight.
A heaver bullet can drop more than a lighter bullet, in air at a given range and velocity.
A lighter bullet can drop more than a heaver bullet, in air at a given range and velocity.
Two bullets of different color can have the same BC.
Two bullets of different BC can have the same color.
A red bullet can drop more than a yellow bullet, in air at a given range and velocity.
A yellow bullet can drop more than a red bullet, in air at a given range and velocity.
It a bullet had no weight, it wouldn't drop, and it would have a BC of zero.
So weight does have an effect in a sense, you have me there.
All bullets do not drop the same amount in a given time unless they are travelling through vacuum. Aerodynamic drag has both a vertical and horizontal component.
Two falling objects of different mass will be acted upon identically by the force of gravity. However, air resistance will act on them differently if they do not have the same ballistic coefficient. I that case, the two objects will accelerate towards the earth at different rates.
Two falling objects of different mass will be acted upon identically by the force of gravity. However, air resistance will act on them differently if they do not have the same ballistic coefficient. I that case, the two objects will accelerate towards the earth at different rates.
Edit: OK, I'm sorry I started this I don't want to bump the thread up with my foolishness.
Take a peanut and a quarter. Stand on a chair. Drop the bullet and the quarter from about 85 inches. Do they hit the ground 6" apart? You don't need a computer.
True, but the bullet travels forward a kilometer in the time it drops 10 meter, and drag is approximately proportional to velocity. So there is precious little downwards difference in a vacuum. Apart from breath control.
BC is proportional to mass, and inversely proportional to cross-sectional area. So it is proportional to the length of the bullet, if the shape is constant.
So drop per 100 yards is affected by the length of the bullet. Kinda.
Edit: For what it is worth:
http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=650
Golfball 5m drop in air 1.02 seconds
Golfball 5m drop in vacuum 1.01 seconds
A golfball is less streamlined than a bullet so the difference will be way less than 1% for the bullet. 1% being 5mm here.
So I'll offer you 2mm difference in drop at after one second (~700m) with a high BC bullet in air versus vacuum. Maybe 1mm after 1 second, low BC vs high BC in air.
If anybody has better math, I'm all ears. I'd love to see an exact answer
I don't want to bump the thread up with my foolishness.Take a peanut and a quarter. Stand on a chair. Drop the bullet and the quarter from about 85 inches. Do they hit the ground 6" apart? You don't need a computer.
True, but the bullet travels forward a kilometer in the time it drops 10 meter, and drag is approximately proportional to velocity. So there is precious little downwards difference in a vacuum. Apart from breath control.
BC is proportional to mass, and inversely proportional to cross-sectional area. So it is proportional to the length of the bullet, if the shape is constant.
So drop per 100 yards is affected by the length of the bullet. Kinda.
Edit: For what it is worth:
http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=650
Golfball 5m drop in air 1.02 seconds
Golfball 5m drop in vacuum 1.01 seconds
A golfball is less streamlined than a bullet so the difference will be way less than 1% for the bullet. 1% being 5mm here.
So I'll offer you 2mm difference in drop at after one second (~700m) with a high BC bullet in air versus vacuum. Maybe 1mm after 1 second, low BC vs high BC in air.
If anybody has better math, I'm all ears. I'd love to see an exact answer
Last edited:
Let's see what actual ballistics calculations can tell us. I found this external ballistics calculator:
http://www.handloads.com/calc/
Bullet #1: Weight of 150 grains, BC of .400, MV of 2750 fps
Bullet #2: Weight of 405 grins, BC of .285, MV of 1300 fps
In both cases, I have used the following inputs for both:
-Sight in range of zero
-Sight height on zero
-Zero muzzle elevation
-10 mph wind at 90 degrees to bullet path
-Sea level altitude
-65 F ambient temperature
Maximum distance used is 500 yards with 10 yard increments
Bullet #1 traveled the entire 500 yards in 0.69 seconds and dropped 79.82 inches below line of sight.
Bullet #2 traveled 257 yards in the same time period and dropped 85.2 inches below line of sight.
It does appear that there can be a substantial difference in bullet drop for a given time between two bullets with different weights and BCs.
One other thing to keep in mind is that the effects of drag are greatly increased as velocity increases. This is why there is so little difference in drop time between a golf ball dropped 5m in vacuum and in air. Likewise, a projectile traveling at low velocity relative to a bullet, such as a mortar bomb, will have a trajectory through air much closer to its trajectory in vacuum.
http://www.handloads.com/calc/
Bullet #1: Weight of 150 grains, BC of .400, MV of 2750 fps
Bullet #2: Weight of 405 grins, BC of .285, MV of 1300 fps
In both cases, I have used the following inputs for both:
-Sight in range of zero
-Sight height on zero
-Zero muzzle elevation
-10 mph wind at 90 degrees to bullet path
-Sea level altitude
-65 F ambient temperature
Maximum distance used is 500 yards with 10 yard increments
Bullet #1 traveled the entire 500 yards in 0.69 seconds and dropped 79.82 inches below line of sight.
Bullet #2 traveled 257 yards in the same time period and dropped 85.2 inches below line of sight.
It does appear that there can be a substantial difference in bullet drop for a given time between two bullets with different weights and BCs.
One other thing to keep in mind is that the effects of drag are greatly increased as velocity increases. This is why there is so little difference in drop time between a golf ball dropped 5m in vacuum and in air. Likewise, a projectile traveling at low velocity relative to a bullet, such as a mortar bomb, will have a trajectory through air much closer to its trajectory in vacuum.
Strictly in terms of bullet drop?
Near as I can tell a long barreled 30-378 (or equivalent) loaded with something like a 190gr Berger at something like 3400fps would be about as flat shooting as it gets.
To keep things fair I fiddled with Xbal inputting various combinations from load data taken from pressure tested sources (for way longer than I should have).
Apples to apples the fast 7mm's seem a close second.
I think what the others were trying to say is flat shooting don't mean chit in the real world.
And they would be right!
Near as I can tell a long barreled 30-378 (or equivalent) loaded with something like a 190gr Berger at something like 3400fps would be about as flat shooting as it gets.
To keep things fair I fiddled with Xbal inputting various combinations from load data taken from pressure tested sources (for way longer than I should have).
Apples to apples the fast 7mm's seem a close second.
I think what the others were trying to say is flat shooting don't mean chit in the real world.
And they would be right!
