Hey guys, when i was shooting my 300 wby this weekend some of the groups went like this: at 100 yds 4 shots went into less than .5 inches (suprised the heck out of me :) ) and the point of impact was 3 inches high and 1 inch to the left. At 300 yds 3 shots went into 3 inches and were about 5 inches low and 3 inches to the right. Now, to me this sounds like 6 inches of wind to the right drift at 300 yds, since without wind i would have expected them to hit 3 inches left. with a relatively light wind does that make any sense? if so how the heck do guys shoot any further than that? also i would have expected the group to open up more than that if its drifting that far. Am i just doing something wrong here?

According to the Wind Drift tables listed in the Hornady 5th edition reloading manuals, the following is given:

Assuming your .300 Weatherby is shooting 180 gr boattail soft points (.452 B.C) at an average of 3100 fps and a 10 mph cross wind (90 degree):

Muzzle = 0

50 yds = .1"

100 yds = .5"

200 yds = 1.9"

300 yds = 4.5"

400 yds = 8.3"

500 yds = 13.6"

As you can extrapolate, hitting 3" right at 300 yds when hitting 1" left at 100 yds would work just about right for a 10 mph crosswind from the left.

Now how do you tell what the wind speed is where you are at , and what the wind speed is half way down range and to the target ? Suppose it's not 10mph , but 11.5mph etc.? JAGG

is a flinch a possibility?

Wind drift is tricky, as the benchresters will tell you. I've seen bullets drift more than predicted more often than not, so your amount of drift doesn't surprise me. It's hard to tell what the wind is doing unless you've got wind flags all the way out. Then there's mirage, and what you're seeing may not be what the bullet is seeing.

Another thing. Were you shooting off the same bench at both yardages, or did you have to move back for the 300 yard shots? A different setup can move groups on you.

Note that in kdub's table, wind drift quadruples when the range doubles. Handy rule of thumb.

Bye
Jack

Thanks for your help guys, i was shooting off the same bench (makeshift as it was) and i was definately not flinching, i dealt with that already :P. I guess it just shocked me how much it can actually drift, people who talk about shooting 5-600 yds must know something i dont :D

JAGG, visit a bench rest range some time when they are shooting, there will be wind flags every where. Not much help in the bush though.

Yes, at 500-600 yards, wind drift is measured in feet, not inches. Look in the back of any reloading manual with wind drift tables and you'll be amazed.

Normally in long range matches you can fire sighters and there's a good reason for that..... you just learned something valuable regarding shooting at long range.

Yup, wind drift is THE big variable past 400 yards.
With the advent of reasonably priced laser rangefinders, and computer generated drop charts, finding the holdover or 'clickups' to get the range is not very difficult these days.
Wind drift, however.....
I only shoot at varmints at long range.
One thing that I have found that helps a lot is a high powered scope- like a top magnification of 16X or so. With a 16-20X magnification, you can watch the vegetation out in the target area- gives you some clue about what the wind is doing out there.
IME, mirage will be a problem if you use a scope with more power than a 16 or 20 power top end.

Does choice of bullets make a difference to wind drift? It seems to me that it wouldn't do much good but i seem to remember hearing that people like to use higher B.C. bullets to decrease it. Also would a smaller bullet drift less due to it's smaller cross section from the side?
sorry for my ignorance on this subject and thanks for your patience.

Play with the ballistics calculator for an education.
http://www.beartoothbullets.com/rescources/calculators/balistics/index.htm

Smaller bullets have a lower sectional denesty, so for the same shape, or more properly form factor, they have a lower ballistic coefficent and drift more. On the other hand, a big blunt nosed bullet, like a .458 500 grain, with a low ballistic coefficient (.295) drifts more than a smaller pointed boat-tail. Even the Hornady .22 68 grain beats it, barely (.330).

There's one really tricky bit in wind drift. It's proportional to the actual time of flight to the time of flight in a vacuum. Now drag increases sharply at the sound barrier, so a bullet that is barely subsonic drifts less than one that's barely supersonic. So if you're shooting your .22 Rimfire on a windy day, leave the high speed stuff at home.

If you want to see real drift, use a muzzleloader and round balls. The low BC (.07) and upper transonic velocity really add up.

Here's a very full explanation.
http://www.nennstiel-ruprecht.de/bullfly/index.htm

The chart that kdub posted from Hornady #5 shows considerably less drift than the charts in Hornady #4 and the Beartooth calculator. :confused:

As for reading the wind, old Tony Boyer has twice the Benchrest Hall of Fame points as anyone else. A number of shooters have beat him when conditions are good, but very few have when conditions are bad.
http://www.benchrest.com/hall_of_fame/

Bye
Jack

As has already been mentioned, Ballistic Coefficient plays a big part in how a bullet shakes off the wind. But the most crucial component is time of flight. The longer that bullet is in the air, the more time the wind has to act on it, and the farther it will push it.

Not necessarily. The bullet with the most lag time or (actual time of flight - time of flight in a vacuum) drifts the most. So the subsonic .22 bullet drifts less than the high velocity bullet.

Bye
Jack

Not necessarily. The bullet with the most lag time or (actual time of flight - time of flight in a vacuum) drifts the most. So the subsonic .22 bullet drifts less than the high velocity bullet.

Bye
Jack

Could you run that by me again? If you shot at a 100 yard target with a .22 bullet going subsonic and another identical bullet at a higher velocity, the subsonic bullet would drift less?

I'm just a little confused because even in a vacuum, the higher velocity round has a shorter time of flight, right?

Never mind, I read that (actual time of flight - time of flight in a vacuum) to mean the same thing when it was the difference between the two.

Anyway, for all practical purposes, this shouldn't come into play very often in modern centerfire rifles. I mean everyone's shooting well over the 1100 fps mark.