I had a shoot last spring that got me thinking. After mulling it over I think that ballistic coefficiency is weighted too heavily in ballistic apps and by hunters when selecting a bullet for windy work.
The example was from shooting multiple rifles and bullets in an extremely windy day. Wind force 6-7. I ended up shooting a fairly large sample size out of each rifle too. When BC’s are calculated they of course take into account the sectional density of the projectile. However, the force vector from wind has a different functional sectional density in that path of travel. The cross sectional density matters more and a larger diameter projectile will have greater cross sectional density. Basically a larger caliber even if a shorter bullet has a higher sectional density in that vector (sideways). Long bullets have greater surface area in that (sideways) vector as well. That’s not saying that those bullets can’t have less wind drift but the long sleek bullet isn’t really much sleeker in that direction of travel (from the side). Higher bc does create lower pressure wake to be acted on my wind.
My observations were that lower bc and lighter .224 bullets had less wind drift UNTIL the higher bc bullets caught up on velocity. Then the higher bc bullets had less wind drift. But it wasn’t the higher bc less wind drift for all ranges. For mine the lighter bullet had less wind drift until out past 550 yards and the higher bc bullet overtook it in wind drift very solidly at 700 yards. 69.5 hammer hbc at 2900 fps mz vs 75 eldm 2675 fps mz.
I was also shooting a 30-06 with 168 Barnes bullets with a modest bc of .47 g1 bc. Muzzle velocity was around 2780 fps. Which is around the same bc as the .224 75 eldm but with a much lower form factor. The 30-06 had about 1/5 the amount of wind drift at 500 yards as the 75 eldm in .224. More mass for the wind to move but possibly it’s more a function of cross sectional, sectional density than mass.
The .308 to .223 results weren’t surprising but the lighter .223 vs heavier higher bc was.
Basically, when determining wind drift performance when selecting a projectile I think taking into account the distance where one similar projectile vs the other reaches the same velocity is worth considering even if at the expense of bc. Kind of like how we are adopting bullets and cartridges based on impact velocity of a bullet to suitable range. Maybe add wind performance to that pre check too but consider what threshold bullet starts slower as an indicator of when that wind break even point is.
This could all be bs from a one off shooting experience. But I’ve been trying to figure out some interesting real world wind results for years. Where one bullet that SHOULD buck wind better doesn’t in back to back shooting. Who wants to finance a 1000 yard controlled wind tunnel?
The example was from shooting multiple rifles and bullets in an extremely windy day. Wind force 6-7. I ended up shooting a fairly large sample size out of each rifle too. When BC’s are calculated they of course take into account the sectional density of the projectile. However, the force vector from wind has a different functional sectional density in that path of travel. The cross sectional density matters more and a larger diameter projectile will have greater cross sectional density. Basically a larger caliber even if a shorter bullet has a higher sectional density in that vector (sideways). Long bullets have greater surface area in that (sideways) vector as well. That’s not saying that those bullets can’t have less wind drift but the long sleek bullet isn’t really much sleeker in that direction of travel (from the side). Higher bc does create lower pressure wake to be acted on my wind.
My observations were that lower bc and lighter .224 bullets had less wind drift UNTIL the higher bc bullets caught up on velocity. Then the higher bc bullets had less wind drift. But it wasn’t the higher bc less wind drift for all ranges. For mine the lighter bullet had less wind drift until out past 550 yards and the higher bc bullet overtook it in wind drift very solidly at 700 yards. 69.5 hammer hbc at 2900 fps mz vs 75 eldm 2675 fps mz.
I was also shooting a 30-06 with 168 Barnes bullets with a modest bc of .47 g1 bc. Muzzle velocity was around 2780 fps. Which is around the same bc as the .224 75 eldm but with a much lower form factor. The 30-06 had about 1/5 the amount of wind drift at 500 yards as the 75 eldm in .224. More mass for the wind to move but possibly it’s more a function of cross sectional, sectional density than mass.
The .308 to .223 results weren’t surprising but the lighter .223 vs heavier higher bc was.
Basically, when determining wind drift performance when selecting a projectile I think taking into account the distance where one similar projectile vs the other reaches the same velocity is worth considering even if at the expense of bc. Kind of like how we are adopting bullets and cartridges based on impact velocity of a bullet to suitable range. Maybe add wind performance to that pre check too but consider what threshold bullet starts slower as an indicator of when that wind break even point is.
This could all be bs from a one off shooting experience. But I’ve been trying to figure out some interesting real world wind results for years. Where one bullet that SHOULD buck wind better doesn’t in back to back shooting. Who wants to finance a 1000 yard controlled wind tunnel?
My calculus is horribly rusty. I remember enough to roughly know how much work a shape or something would require and have forgotten enough to not even want to try it. I have my TI 93 somewhere collecting dust.
