22WMR vs .22LR wind drift question

[Occams Rasor]

[nitrous_bob]

its a bigger diameter bullet, so it has more contact area
i never would have guessed that either, seems the velocity alone would negate it

[Excaliburr]

It is all in that ballistic coefficient. The profile/ogive or sectional density of the projectile is different. So, Winchester is using a different bullet in each of the rounds. You have to comapare apples to apples, then the wind drift would be less in the faster round.

[as_rocketman]

To first order, the higher ballistic coefficient of the .22 LR round works to fight the wind in two ways -- first, the wind accelerates it less; and second, it retains more velocity downrange.

While the .22 WMR round is 50% faster at the muzzle, by 50 yards it's only 35% faster, and at 100 yards it's now 30% faster. On average, call it about 35% faster.

Meanwhile, the .22 LR round has a ballistic coefficient that is... 26% higher than the .22 WMR. ( (0.1384 - 0.1099) / 0.1099 = 0.259)

Those two factors just about cancel each other out, at this particular range.

However, we cannot think about the ballistic coefficient as a true constant. It also depends on the bullet speed, since speed affects the bullet's wake, and the wake also interacts with crosswind.

The .22 LR bullet is spending most of its time-in-flight subsonically, whereas the .22 WMR is still sonic out to approximately 155 yards. Subsonic bullets have a smaller effective cross-section.

So the .22 LR actually has a much greater BC advantage over the .22 WMR than it appears from a measurement of the bullet shapes alone.

[Nshaver127]

I like the term Ballistic coefficient. Its physics, aerodynamics whatever. Think about the shape of a .22 wmr. I bet a .17hmr has much less wind drift than both

[as_rocketman]

But .17 HMR is also much lighter. The net Ballistic Coefficient is about the same. However, being much lighter also makes it a lot faster... like twice as fast. So the wind drift of .17 HMR is typically slightly better than .22 LR, and it has a longer effective range.

Ballistic coefficient is an approximation, a shortcut. It's not really a constant. We just treat it like one as a rule of thumb.

[Occams Rasor]

Thanks for all the above input. Starting to make sense now.