Bullet Drift - how far?

T

TFinalshot

Guest
Is there anyway to logically estimate bullet drift over known distance's and wind speeds? I wonder what a 30 MPH cross wind would do to a 150 gr. bullet shot from a 300 WSM at 250, 300, 350, and 400 yards?
I deliberately did not shoot a very nice mule deer buck this weekend because I did not want to wound him. I estimated him to be about 300+ and directly accross canyon. The distance was not a problem, but the 30 mph cross wind, with gusts to 45 was!

As it turned out, I sat on him for more than 3 hours thinking he would get up and move down off the cliff. Well, he got up fed around for about 10-15 minutes and some joker started blazing away at what I thought was at least 400 yard shot, could have been more, (with a 30mph cross wind) and wounded him. I'm not sure they ever found the buck. Last I saw the buck was moving up hill and into the next basin like he'd not been hit. Only problem is I know he was hit cause he went down like a tone of bricks, stayed down for about 2 minutes and then sprang to life and ran off like nothing had happened, go figure!

Finalshot
 
Thanks for the link, it looks useful. I did not find anything specific to my question on that site. Could you point out where on that site I might find an answer to my question?

Finalshot
 
You can get information on bullet drift from a variety of sources. Several of the reloading manuals have that data in the back of the books. The tricky part is estimating wind speed, even if you know the distance. Winds vary across canyons and they gust. At best, it is a "crap shoot" to shoot bucks over 300 yards in high winds. I live in a very windy area of southeast Wyoming and experience has taught me to get close and be comfortable or pass the shot. It sounds like you were on the right track until the other hunter opened up.
 
You want to download the PointBlank Ballistics program from HuntingNut. One of the data output pages shows wind drift from 0-1000 yards at various wind increments.

Side note: I wrote this program :)


-DallanC
 
Tfinale, I have seen deer go down like they were pole axed and then get up and run away. Sometimes the slightest nick on a foreleg , under the belly or somewhere else on a deer can look like a truck hit them and they go down. If he ran off like he wasn't hurt then MAYBE (WE HOPE) he wasn't. Unless you know they eventually got him?. I hunt in country that can occasionally get windy and it's a hard call. Usually wind won't blow consistantly and you can get a good shot off during a lull. I think you did the right thing though. If your not sure don't shoot. There will always be other bucks. Good call....
 
Final Shot

When you get the ballistics done, compare it to 180 and 200s, even 165s. You'll find better wind bucking bullets than the 150 especially at 300 and beyond. The drops you can handle. Thats easy by a chart and rangefinder. The wind becomes much more interesting.

I don't have a program at work, but just guessing, I'll guess the wind could be as bad as 36-48 inches under those conditions.

I'll run my Pejsa program at home and see how it compares to Dallans program later tonite if I remember.

Jeff
 
Can't use Dallans program since I only have macs.

On my Pejsa program I've gotten good enough data for first round Xs out to 1000 yards with match rifles for drop and drift charts so its pretty reliable.

First off, 150s with assumed MV at 3200.
300 yards, 30mph 16", 40mph 21",45mph 23"
400 yards , 30mph 28", 40mph 37", 45mph 42"
600 yards, only did 45 mph for some reason, 105 "

Now move up to 180s and slow down about 150 fps
300 yards, 30 is 12",40 is 16",45 is 18"
400 yards, 30 is 20",40 is 29", 45 is 33"
600 yards only 45mph is 78"

I forgot to note drop differences but they are mimimal enough and as stated earlier you can get solid data there by shooting and recording drops and using a rangefinder.

The drifts are much better than I had thought, but I don't often shoot mags. Normally just 223 with 90s out to 1000 in matches.

Still it always becomes a challenge in the wind at 300 and beyond. Miss the wind and you can go from vitals to guts or worse in a hurry. The big bullets don't give that much of an advantage but they will retain more energy and the further out you get the larger the advantage gets. The lighter faster ones just run out of steam quicker. Kind of related to smashing a shuttlecock and a tennis ball. In a round about way.

Jeff
 
Jeff, and others,

Thanks for all the help. Jeff, your research will help me at when I get to the range. I plan to head out durring a strong cross wind and do some shooting. Thanks again for all your help, I only wish I would have thought of asking a year ago!

Finalshot
 

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