I have read several threads that suggests that one bullet weight (.308) over another is superior, depending on the distance you shoot. Maybe I'm missing something, but it seems like the bullet that is on target at 1000 yards will be right on target at 100 yards. Isn't .25 MOA at 1000 still .25 MOA at 100. I just don't see how a round can get more accurate over distance. I understand a lighter round may deflect more over distance, but if your round is dead on at 1k, why wouldn't it be great at 100.
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Why different weights for different distances
- Thread starter heydavemd
- Start date
Re: Why different weights for different distances
Complex answer=pages long
short answer
heavier bullets "usually" have higher BC meaning less drift less compensation at distance. Lighter bullets "usually" mean higher velocity less time in flight less correction at shorter distances. All this is based on a HUGE amount of variables to long to list like twist rates, powder, pressure, enviro, stabilization at distance (going to sleep) so a good long distance bullet may not group as well short as it does long etc. etc. etc. etc.
Complex answer=pages long
short answer
heavier bullets "usually" have higher BC meaning less drift less compensation at distance. Lighter bullets "usually" mean higher velocity less time in flight less correction at shorter distances. All this is based on a HUGE amount of variables to long to list like twist rates, powder, pressure, enviro, stabilization at distance (going to sleep) so a good long distance bullet may not group as well short as it does long etc. etc. etc. etc.
Re: Why different weights for different distances
A bullet does not get more accurate over distance, in the real world, bullets accuracy will degrade over distance over distance as environmental conditions have time to play with the bullet.
A bullet designed for the long distance may not be quite as accurate as a bullet designed for pure accuracy at the shorter distance. For example, the nechresters seem to favor short flat base bullets that require lazy twist rates to stabilize at 100 and 200 yards. A slow spin rate reduces or eliminates any wobbling (dynamic instability) in a bullet and when group sizes are measure in hundreths of inches, everything counts.
The reason we cannot uses these bullets at the longer ranges is that their BC is so low, the bullets lose all their velocity in a few hundred yards. Regardless of how fast you start a low BC bullet, it sheds its forward velocity very quickly. So it does not matter how accurate a bullet is, if it can't get to the target or is so slow it gets tossed around by the wind and such.
For those long distances, we turn to long for caliber bullets, because that's how you increase the ballistic coefficient; you increase the sectional desnity and there are only two ways to do that, use longer (heavier) bullets or use denser material.
Until such time as they sell depleted uranium (DU) on the open market, or gold or tungsten prices go down some, we're pretty much stuck with lead and option 1. Longer bullets also allow the bullet designer to make it even more aerodynamic, further enhancing the BC.
Now, higher BC bullets are more unstable than lower BC bullets, and with the much higher sin rates required to stabilize them come issues of possible dynamic instability. However, bullets manufactured today are very high quality, but some can still get out where there is a pocket or some issue with the jacket. I know because that is standard excuse #31 why my shot on target was poor and I am not afraid to use it.
Another issue is that a long heavy bullet will recoil a little more compared to a lighter bullet and if you do not intend to go beyond a certain distance it's wise to pick a bullet that is more suited to the distance.
For instance I use two bullets in my match .308 rifle and the are both 180gr and above match bullets. I only shoot at 100 yards during load development. I only compete from 600 to 1000 yard so that is why I use these bullets. If I shot at 300 yards or less with this rifle, I would be tempted to use a 150gr bullet.
There is much more to discuss, but I hope this gives you an idea.
A bullet does not get more accurate over distance, in the real world, bullets accuracy will degrade over distance over distance as environmental conditions have time to play with the bullet.
A bullet designed for the long distance may not be quite as accurate as a bullet designed for pure accuracy at the shorter distance. For example, the nechresters seem to favor short flat base bullets that require lazy twist rates to stabilize at 100 and 200 yards. A slow spin rate reduces or eliminates any wobbling (dynamic instability) in a bullet and when group sizes are measure in hundreths of inches, everything counts.
The reason we cannot uses these bullets at the longer ranges is that their BC is so low, the bullets lose all their velocity in a few hundred yards. Regardless of how fast you start a low BC bullet, it sheds its forward velocity very quickly. So it does not matter how accurate a bullet is, if it can't get to the target or is so slow it gets tossed around by the wind and such.
For those long distances, we turn to long for caliber bullets, because that's how you increase the ballistic coefficient; you increase the sectional desnity and there are only two ways to do that, use longer (heavier) bullets or use denser material.
Until such time as they sell depleted uranium (DU) on the open market, or gold or tungsten prices go down some, we're pretty much stuck with lead and option 1. Longer bullets also allow the bullet designer to make it even more aerodynamic, further enhancing the BC.
Now, higher BC bullets are more unstable than lower BC bullets, and with the much higher sin rates required to stabilize them come issues of possible dynamic instability. However, bullets manufactured today are very high quality, but some can still get out where there is a pocket or some issue with the jacket. I know because that is standard excuse #31 why my shot on target was poor and I am not afraid to use it.
Another issue is that a long heavy bullet will recoil a little more compared to a lighter bullet and if you do not intend to go beyond a certain distance it's wise to pick a bullet that is more suited to the distance.
For instance I use two bullets in my match .308 rifle and the are both 180gr and above match bullets. I only shoot at 100 yards during load development. I only compete from 600 to 1000 yard so that is why I use these bullets. If I shot at 300 yards or less with this rifle, I would be tempted to use a 150gr bullet.
There is much more to discuss, but I hope this gives you an idea.
Re: Why different weights for different distances
I originally thought this several years ago also and turned out I was wrong as you are. Shooting is a constant learning procedure. Here is a basic and very well done look at the "Epicyclic" motion of a bullet by in my opinion a genius in the ballistics field Bryan Litz. I would suggest you get his book it is fantastic. It is also discussed in depth in a very good book called "Complete .50-Caliber Sniper Course : Hard-Target Interdiction" by a "controversial" person on the hide right now Dean Michaelis http://www.amazon.com/exec/obidos/ISBN=1581600682/snipercountryA
Here is a little bit of what a bullet looks like as it "goes to sleep"
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=937430
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sig685</div><div class="ubbcode-body">A bullet does not get more accurate over distance, in the real world, bullets accuracy will degrade over distance over distance as environmental conditions have time to play with the bullet.
A bullet designed for the long distance may not be quite as accurate as a bullet designed for pure accuracy at the shorter distance. For example, the nechresters seem to favor short flat base bullets that require lazy twist rates to stabilize at 100 and 200 yards. A slow spin rate reduces or eliminates any wobbling (dynamic instability) in a bullet and when group sizes are measure in hundreths of inches, everything counts.
The reason we cannot uses these bullets at the longer ranges is that their BC is so low, the bullets lose all their velocity in a few hundred yards. Regardless of how fast you start a low BC bullet, it sheds its forward velocity very quickly. So it does not matter how accurate a bullet is, if it can't get to the target or is so slow it gets tossed around by the wind and such.
For those long distances, we turn to long for caliber bullets, because that's how you increase the ballistic coefficient; you increase the sectional desnity and there are only two ways to do that, use longer (heavier) bullets or use denser material.
Until such time as they sell depleted uranium (DU) on the open market, or gold or tungsten prices go down some, we're pretty much stuck with lead and option 1. Longer bullets also allow the bullet designer to make it even more aerodynamic, further enhancing the BC.
Now, higher BC bullets are more unstable than lower BC bullets, and with the much higher sin rates required to stabilize them come issues of possible dynamic instability. However, bullets manufactured today are very high quality, but some can still get out where there is a pocket or some issue with the jacket. I know because that is standard excuse #31 why my shot on target was poor and I am not afraid to use it.
Another issue is that a long heavy bullet will recoil a little more compared to a lighter bullet and if you do not intend to go beyond a certain distance it's wise to pick a bullet that is more suited to the distance.
For instance I use two bullets in my match .308 rifle and the are both 180gr and above match bullets. I only shoot at 100 yards during load development. I only compete from 600 to 1000 yard so that is why I use these bullets. If I shot at 300 yards or less with this rifle, I would be tempted to use a 150gr bullet.
There is much more to discuss, but I hope this gives you an idea.</div></div>
I originally thought this several years ago also and turned out I was wrong as you are. Shooting is a constant learning procedure. Here is a basic and very well done look at the "Epicyclic" motion of a bullet by in my opinion a genius in the ballistics field Bryan Litz. I would suggest you get his book it is fantastic. It is also discussed in depth in a very good book called "Complete .50-Caliber Sniper Course : Hard-Target Interdiction" by a "controversial" person on the hide right now Dean Michaelis http://www.amazon.com/exec/obidos/ISBN=1581600682/snipercountryA
Here is a little bit of what a bullet looks like as it "goes to sleep"
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=937430
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sig685</div><div class="ubbcode-body">A bullet does not get more accurate over distance, in the real world, bullets accuracy will degrade over distance over distance as environmental conditions have time to play with the bullet.
A bullet designed for the long distance may not be quite as accurate as a bullet designed for pure accuracy at the shorter distance. For example, the nechresters seem to favor short flat base bullets that require lazy twist rates to stabilize at 100 and 200 yards. A slow spin rate reduces or eliminates any wobbling (dynamic instability) in a bullet and when group sizes are measure in hundreths of inches, everything counts.
The reason we cannot uses these bullets at the longer ranges is that their BC is so low, the bullets lose all their velocity in a few hundred yards. Regardless of how fast you start a low BC bullet, it sheds its forward velocity very quickly. So it does not matter how accurate a bullet is, if it can't get to the target or is so slow it gets tossed around by the wind and such.
For those long distances, we turn to long for caliber bullets, because that's how you increase the ballistic coefficient; you increase the sectional desnity and there are only two ways to do that, use longer (heavier) bullets or use denser material.
Until such time as they sell depleted uranium (DU) on the open market, or gold or tungsten prices go down some, we're pretty much stuck with lead and option 1. Longer bullets also allow the bullet designer to make it even more aerodynamic, further enhancing the BC.
Now, higher BC bullets are more unstable than lower BC bullets, and with the much higher sin rates required to stabilize them come issues of possible dynamic instability. However, bullets manufactured today are very high quality, but some can still get out where there is a pocket or some issue with the jacket. I know because that is standard excuse #31 why my shot on target was poor and I am not afraid to use it.
Another issue is that a long heavy bullet will recoil a little more compared to a lighter bullet and if you do not intend to go beyond a certain distance it's wise to pick a bullet that is more suited to the distance.
For instance I use two bullets in my match .308 rifle and the are both 180gr and above match bullets. I only shoot at 100 yards during load development. I only compete from 600 to 1000 yard so that is why I use these bullets. If I shot at 300 yards or less with this rifle, I would be tempted to use a 150gr bullet.
There is much more to discuss, but I hope this gives you an idea.</div></div>
