It is a fact that a slower velocity bullet is more accurate in the wind.
Why is this? Thank you.
muzzle velocity vs accuracy
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muzzle velocity vs accuracy
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Re: muzzle velocity vs accuracy
The maths is above my pay grade, but it's related to air resistance, and loss of velocity. There's a better explanation here: http://www.thewindisnotyourfriend.com/r ... -wind.html
Re: muzzle velocity vs accuracy
Even after reading the explanation, the effect is still not intuitive to me. I have used JBM Ballistics, the on line ballistics calculator, to run the experiment.
The math says that changing from 1050 to 1090 fps causes wind deflection to increase 0.3 inches at 100 yards and 0.1 inches at 50 yards.
Interesting.
The math says that changing from 1050 to 1090 fps causes wind deflection to increase 0.3 inches at 100 yards and 0.1 inches at 50 yards.
Interesting.
Re: muzzle velocity vs accuracy
It is not so much accuracy, as effect of wind. In constant wind, there is no reason for accuracy to be different. At least that I can figure.
Re: muzzle velocity vs accuracy
High velocity 0.22LR is usually less accurate because it's cheap, and the factory hasn't spent the same time and effort of producing high quality components and developing a good load.
Re: muzzle velocity vs accuracy
Its an interesting discussion....... Drag squares as velocty doubles. Projectiles have 2 shock waves.
Very fast bullets lose velocity at a faster rate than slower projectiles...... This means that the faster bullets will have larger center of pressure movements than slower bullets. As bullets go supersonic, the shock waves get very close together, as they become transonic they move apart until they are subsonic and have a leading edge and trailing edge shock wave. This CP movement causes more bullet drift because there is more energy in tbe shock wave to create lift due to assymetric air pressure on the sides of the bullet. The differences in the lift caused by tbe interaction with tbe aparrent wind moves the bullet in tbe direction of wind at a rate higher than the wind itself, and as velocity gos up, the drift is even more pronounced because of that whole drag and velocity squared thing giving the bullet more movement the faster it is going.......
Think of a curve ball being thrown ..... The ball is rotating, so the shock wave of tbe ball is much more pronounced on tbe side of tbe ball moving forward....... The side of tbe ball moving aft has a much less pronounced pressure signature. The interaction between the higher energy pressure wave and ambient pressure pushes tbe ball laterally towards the low energy side of tbe ball....... Throw a curve ball faster, tbe pressure wave differences go up as tbe square of tbe velocity so it moves a lot farther...... Same with a bullet, the crosswind creates a pressure differential and the side being hit by the relative wind creates lift pushing the bullet to the downwind side of the projectile...... Tbe more the wind, and with forces going up as a square of the velocity change, the more distance the projectile will move laterally per the same unit time ........
Very fast bullets lose velocity at a faster rate than slower projectiles...... This means that the faster bullets will have larger center of pressure movements than slower bullets. As bullets go supersonic, the shock waves get very close together, as they become transonic they move apart until they are subsonic and have a leading edge and trailing edge shock wave. This CP movement causes more bullet drift because there is more energy in tbe shock wave to create lift due to assymetric air pressure on the sides of the bullet. The differences in the lift caused by tbe interaction with tbe aparrent wind moves the bullet in tbe direction of wind at a rate higher than the wind itself, and as velocity gos up, the drift is even more pronounced because of that whole drag and velocity squared thing giving the bullet more movement the faster it is going.......
Think of a curve ball being thrown ..... The ball is rotating, so the shock wave of tbe ball is much more pronounced on tbe side of tbe ball moving forward....... The side of tbe ball moving aft has a much less pronounced pressure signature. The interaction between the higher energy pressure wave and ambient pressure pushes tbe ball laterally towards the low energy side of tbe ball....... Throw a curve ball faster, tbe pressure wave differences go up as tbe square of tbe velocity so it moves a lot farther...... Same with a bullet, the crosswind creates a pressure differential and the side being hit by the relative wind creates lift pushing the bullet to the downwind side of the projectile...... Tbe more the wind, and with forces going up as a square of the velocity change, the more distance the projectile will move laterally per the same unit time ........
Re: muzzle velocity vs accuracy
to "spektr" re your explanation.....THANK YOU for a very fluent explanation of the relationship between muzzle velocity and point of impact. Have always wondered about this. Do you think that a muzzle velocity of 1080 vs 1055 is significant enough to affect the point of impact enough to be a determining factor in competition? This question comes from smallbore shooting... 22LR at 50 and 100 yards. Both Lapua and Eley, ammo makers, have a testing tunnel where they can very accurately test the group size of a 22LR ammo lot. What I question is "Does a smaller group size therefore mean that I ought to buy this lot number?" OR... is the effect of "wind while shooting" a strong enough factor to negate the benefit of a smaller group size with the faster ammo?" Hope that makes sense... My thinking as a shooter is to favor the slower speed bullet because it will not be as affected by the wind as a faster speed.... BUT... having said this, I'm trying to know if my "logic" is correct or am I simply overthinking this entire issue. To say the same question another way: if a "high speed muzzle velocity" lot, (1075 - 1080), demonstrates (in my rifle) the smallest group size, should I buy that OR.... should I simply test the slower speed ammo, (1055) until I find the lot number that gives me the group size I'm looking for? Is the difference between 1080 and 1055 going to be a significant determining factor when shooting in the wind? again... Thank you for your input !!
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Re: muzzle velocity vs accuracy
40X Guy,
Do the US test centres chronograph ammunition as you shoot? If not can you be sure that a 1055fps rated batch will shoot slower than a 1080fps batch in your barrel? Remember the published velocity for a batch is the manufacturer's data, usually an average from several test barrels.
Do the US test centres chronograph ammunition as you shoot? If not can you be sure that a 1055fps rated batch will shoot slower than a 1080fps batch in your barrel? Remember the published velocity for a batch is the manufacturer's data, usually an average from several test barrels.
Re: muzzle velocity vs accuracy
To 40x guy......
Here is where smallbore shooting gets obscene.....
The velocity of a smallbore round in zero wind is somewhat irrelevant. The Std Deviation in velocity matters more...... If every bullet went the exact same speed, they would make a jagged hole and you would be happy.
In the wind the velocity STD Deviation becomes more important.........
Then again there are other things going on......
Is the bullet shape after obduration in your gun a food shape. Is the hardness of that bullets lead in your barrel a food match. Is the rim thickness letting you get perfect clamp up of the round so it is coaxial with the bore axis. Is the chamber cut to hold a round tightly, or does it best fit itself.......
This stuff explains why Bliekers have a hydraulic clamping bolt. They are striving for repeatability..... It also explains why Anschutz doesnt have a hydraulic bolt, they are striving for repeatability in different ways.....
Many rabbit holes
There is also the human interface, some guns and I get along and Im lights out with them. B Others speak a different language and I cant hit Xs to save my life......
Ultimately you need to conquer variability, not necessarily find the best single setup, because people are actually variable and that means the best single setup....... Is in fact....... Variable
Here is where smallbore shooting gets obscene.....
The velocity of a smallbore round in zero wind is somewhat irrelevant. The Std Deviation in velocity matters more...... If every bullet went the exact same speed, they would make a jagged hole and you would be happy.
In the wind the velocity STD Deviation becomes more important.........
Then again there are other things going on......
Is the bullet shape after obduration in your gun a food shape. Is the hardness of that bullets lead in your barrel a food match. Is the rim thickness letting you get perfect clamp up of the round so it is coaxial with the bore axis. Is the chamber cut to hold a round tightly, or does it best fit itself.......
This stuff explains why Bliekers have a hydraulic clamping bolt. They are striving for repeatability..... It also explains why Anschutz doesnt have a hydraulic bolt, they are striving for repeatability in different ways.....
Many rabbit holes
There is also the human interface, some guns and I get along and Im lights out with them. B Others speak a different language and I cant hit Xs to save my life......
Ultimately you need to conquer variability, not necessarily find the best single setup, because people are actually variable and that means the best single setup....... Is in fact....... Variable