Bullet Drift

Shooting a 7mm Mag, factory Federal premiums w/ 150 grain boattail bullets.

300 yard +/- shot, 25 mph crosswind.

How far will the bullet drift from the wind?

Roughly 13 inches

Thanks 300Winnie.

Did you figure that out from experience or are there some ballistic charts somewhere?

Also, is the drift a function of bullet weight/velocity to wind (i.e. a different caliber but same bullet weight and FPS would drift the same?)

Thanks again....my recent experience shows a little further drift but the exact wind speed was unknown and the deer was at a slight angle. Hit him WAY back from where I was aiming.

Drift is mainly a function of 1. obviously wind speed. 2. velocity, ie, bullet time of flight. 3.distance 4.the bullets BC, ie, how aerodynamic is the bullet, bullets with a high bc will shoot flatter, retain velocity better, and drift less.

I use a program called point blank. It is a free download. I believe the website is www.huntingnut.com

200 yards you are normally safe. At 300 yards wind becomes a major factor.

Factor in actual speed, gusts, any kind of unseen wind(IE gullies or draws coming in elevate wind speed at that area)and then take in your average group size at 300 yards and your wobble area.

Given that drift could be said to be 12 inches, and then your group size is probably AT LEAST 3 inches for a group at 300. Maybe more. And you don't have a bench rest, so your wobble is at least close to 2moa(IE 6 inches) if you factor the extremes in from this example you could easily be 18-20 inches off.

For anyone shooting 300yards or beyond you need a great depth of info on the gun, load and the conditions. How does the tempertature effect your elevation?? What is wind speed? What speed causes smoke to drift, what causes grass or leaves to move, what causes limbs to move. What causes trees to sway. What angle is the snow or rain falling at can help guess speeds. A wind speed meter can be even more precise.

IT takes a lot of ethics and responsibility to be 110% confident in longer shots. You've seen the result. The result could have been even worse if you never recovered the animal. As it is there was probably a finishing shot required as you didn't make it perfect the first time.

Be totally sure of your equipment and shot before shooting.

Example-- I shoot a lot. 300 is no big deal to me. IF there is ANY wind I know its gonna be probably at least worth 3-6 inches of drift if its noticeable wind. I also know my 300 mag will not shoot the first round in the group. So I fouled my gun the other day-- first round out right like normal. Second about half inch low at 300. Dead on. Thats 80degrees. I know that if we get as low as freezing that the group will now be about 3-4 inches low at 300 yards. I simply favor.

So you see that its much more complicated than one would initially think. I use similar examples in my hunter ed classes. Most folks won't shoot past 200 after we've done a few drills. Probably 80-90% don't factor enough wind in. Its sure an eye opener.

BEst, Jeff

You can also go to handloads.com/calc and put in the info and it will calculate it for you. Steve

Been out for awhile, so thanks to all for the replies.

Jeff, I agree with what you are saying, although to be honest some of it (i.e. MOA, etc) went over my head. And your right, the first shot was far from perfect and required a follow-up, although the deer went down and did not move from the spot.

I have made one shot kills as far away as 410 yards (range finder)so this shot was within reason but I did not factor in the wind at all. I had even thought about it earlier in the day but when there is a deer standing on the hill, and its "time", you tend to forget.

It would just seem strange to shoot 12" in front of a deer that is not moving, but that is exactly what I should have done.

Thanks again.