The heavier the bullet the less it is affected by wind....
Nope, it is time of flight alone that determines wind drift. Time of flight depends on velocity and bullet drag - not bullet weight. Examples from the Hornady #6 Manual drift tables:
.270 WCF - 130SST(BC=.460) @ 3100 fps - drift at 300 yards = 4.4"
.35 Whelen - 225XXX(BC=.403) @ 2800 fps - drift at 300 yards = 6.0"
Sorry, wind drift was not the reason for the larger .270 groups.
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I know what you are saying is true for trajectory becuse the ACCELERATION of gravety (9.8 m/s squared) is constant on both bullets. I am not sure the ACCELERATION caused by a latteral wind would be the same on bullets of two different weights? I am not saying you are wrong, just not sure that it makes intuitive sense to me. What is the drift of the 140 grn 270 bullet driven at the same velocity (2800 ie same time of flight)? If what you say is true, I would expect it to be almost identical to the 6" but just slightly better because of the balistic coeficient.
It has been a while since I have actually looked at one, but I thought Usually those tables rank order drift in a given caliber being less with heavier bullets which fly slower. That would imply that BC has a greater impact on drift than velocity (time in flight)?
I am not looking to be confrontational, I am asking more than stating?
Input appreciated.
That is what I was refering to in my first post, but it is BC & not weight, High BC usually mean heavier bullets, but not allways due to shape & some heavy flat nose bullets have very low BC values.
And again, you can compare 2 calibers with one having a much heavier bullet, for example a 225gr 338 vs a 140gr. 270, & if the BC & the velocity
is the same (in some cases very close), then the traj. & wind drift will be the same.
Bullet weight is not the issue at all, BC & Vel. is. I am looking at a #5 Hornady manual, looking at the wind drift chart you will see that they will give the BC value of a bullet for each chart & list the wind drift in 100yd. increments at a given velocity. The
ONLY 2 Factors needed in the wind drift
calculation is BC & VELOCITY,PERIOD. That takes care of wind drift. Weight & caliber is not the issue.
When you look at the Trajectory of a bullet, you can set up charts with the very same variables,
BC & Velocity. Speer has made charts like that for years, they would show A given BC & then the velocity in 100fps increments. I like this chart because I can plug in other brand bullets if I have the BC level & know the velocity.
So in both the Hornady wind drift charts & the Speer trajectory charts, you can use the data for any brand bullet, regardless of caliber & weight & just match up the BC & Vel, kind of neat.
Bottom line is the velocity & BC are the factors & they don't care what the caliber or weight is. That being said, we have a good combination of vel & BC with the heavier 6.5, 7mm & 30 cal. bullets with corespondingly bigger cases.
At ranges under 500 yards & especially under 400 yards, the very high vel. rounds like the the 204 & 220 Swift are very impressive in trajectory & up to 300 or so in wind drift too, because of vel/time of flight. That is why newbies & & those that shoot at more typical yardages get all giddy over factory traj. charts.
But the longer the range, the more bc takes over in both traj. & wind. That is why long range shooters like thos sleek, high BC bullets & do better even when giving up a little velocity.
