Bullet Weight, Speed and Wind

[Sir Henry]

I've heard arguments both ways on whether a lighter faster bullet would have more windage than a heavier slower bullet. I'm in the lighter faster bullet being more stable group. My reasoning is that a 55 grain bullet would be in the wind for less time in 200 yards than a heavier slower 70 grain bullet. Yes at some point the lighter bullet would be going slower than the heavier bullet but I'm only talking about total time from muzzle to 200 yards.

So who knows science and the laws of motion?

[JEBar]

being married to a physics teacher does have some advantages .... well, at least in some areas .. .. pull the trigger on any regular firearm that is positioned so that the barrel is parallel to the ground .... at the instant the bullet exits the muzzle, drop the same bullet from the height of the muzzle above the ground, the two bullets will hit the ground at the same instant .... the distance the bullet will travel is different, no the time in the air ..... gravity is gravity .... that doesn't address wind drift but it does give a pretty good picture of how long the wind would have to work on the bullet

[Sir Henry]

being married to a physics teacher does have some advantages .... well, at least in some areas .. .. pull the trigger on any regular firearm that is positioned so that the barrel is parallel to the ground .... at the instant the bullet exits the muzzle, drop the same bullet from the height of the muzzle above the ground, the two bullets will hit the ground at the same instant .... the distance the bullet will travel is different, no the time in the air ..... gravity is gravity .... that doesn't address wind drift but it does give a pretty good picture of how long the wind would have to work on the bullet

Wind is like gravity in the fact that weight really doesn't matter. Would a 300 grain bullet hit the ground before a 240 grain bullet? More important to weight is surface area. If the surface area of the two bullets is the same the lighter bullet would be pushed off course more. But if the surface area is the same ratio as the weight they would hit the same spot.

Common sense tells us the opposite.

[tractortad]

I majored in Physics in college and after thinking about this, I have no idea...Probably depends a lot on the ballistic coefficient of the bullet. I bet the long range/precision rifle shooting crowd has the answer - like comparing a 6.5 Creedmore vs. a .308 bullet at long range...

[CT_Shooter]

It appears that the effect of wind on a bullet can't be easily isolated from the many other variables involved in the answer. Physics students enjoy.

https://en.wikipedia.org/wiki/External_ballistics#Wind

"Wind has a range of effects, the first being the effect of making the projectile deviate to the side (horizontal deflection). From a scientific perspective, the "wind pushing on the side of the projectile" is not what causes horizontal wind drift. What causes wind drift is drag. Drag makes the projectile turn into the wind, much like a weather vane, keeping the centre of air pressure on its nose. This causes the nose to be cocked (from your perspective) into the wind, the base is cocked (from your perspective) "downwind." So, (again from your perspective), the drag is pushing the projectile downwind in a nose to tail direction.

Wind also causes aerodynamic jump which is the vertical component of cross wind deflection caused by lateral (wind) impulses activated during free flight of a projectile or at or very near the muzzle leading to dynamic imbalance.[53] The amount of aerodynamic jump is dependent on cross wind speed, the gyroscopic stability of the bullet at the muzzle and if the barrel twist is clockwise or anti-clockwise. Like the wind direction reversing the twist direction will reverse the aerodynamic jump direction.

A somewhat less obvious effect is caused by head or tailwinds. A headwind will slightly increase the relative velocity of the projectile, and increase drag and the corresponding drop. A tailwind will reduce the drag and the projectile/bullet drop. In the real world, pure head or tailwinds are rare, since wind is seldomly constant in force and direction and normally interacts with the terrain it is blowing over. This often makes ultra long range shooting in head or tailwind conditions difficult."

[Sir Henry]

The article says the wind pushing on the side of the projectile is not what causes horizontal wind drift. Maybe not but a side wind on my car sure pushes it to the side.

[North Country Gal]

My concern with shooting when there is a breeze or wind is not bullet drift. On something like a 223 at a relatively short distance of 200 yards, actual bullet drift isn't much of a factor. If it was as easy as calculating bullet drift, we could just adjust windage on our sights and go ahead and shoot great groups.

What is a factor on a windy day or even on a mildly breezy day is atmospheric instability. Wind is a manifestation of that. Even on a relatively calm day, the air between you and the target is rarely a constant all the way to the target. On a windy day, especailly, the wind at your shooting station is usually NOT the same as the wind at the target. This changing and shuffling of the air between you and the target absolutely opens up group size. On a day with wind or even a breeze, pretty darn hard for two successive bullets to encounter exactly the same air conditions on the way to the target. This is why it's tough to shoot those wall hanger groups on a windy day.

There is no better way to learn this than to try shooting air guns at 50 yards. Those very light pellets are easily buffeted by unstable and changing air currents on their way to the target. I have wind flags posted next to my 35 yard and 50 yard targets. Amazingly, the flags between the two distances, only separated by 15 yards, will often indicate different wind speeds and, sometimes, even different wind directions at the same instant. If I hope to have any chance of shooting a good group, I have to be very patient and wait for both flags to show little air movement. Even more amazing, even on dead calm days, with both flags motionless, I still have to sometimes contend with rising air from ground that is warming. Even that is enough to affect pellet accuracy.

You can do all the math you want, but the those variables change for every shot because the atmosphere between you and the target is seldom a constant. It's constantly moving on most days. Windy days are especially turbulent. That's the problem.

[RanchRoper]

Ugh....math...head hurts...

[JEBar]

Would a 300 grain bullet hit the ground before a 240 grain bullet?

the pull of gravity on a falling object is constant, 32 feet per second, per second .... without extenuating circumstances like one item having a parachute, the 300 gr and the 240 gr bullets dropped from the same height at the same time would hit the ground at the same time