Effects Down Range: dealing with the great equalizer...WIND.
So far we have determined that developing a load with the lowest standard deviation in muzzle velocity is important since with “no wind” models it translates to fewer high or low misses. We have also determined that under ideal conditions 100fps may be worth as much as a small boost in ballistic coefficient; at least that is the party line in some SML circles that “know” a lot about long range shooting. Up until now we have modeled ideal conditions. That is to say, bluebird skies and no winds. Unfortunately, in my experience, those conditions never present themselves to me during the late fall and winter. It is usually cold and windy where I have hunted so we are about to take our chosen loads head to head with the conditions they will face when it counts.
Wind is the great equalizer. It is hard for everyone to deal with and it is the only thing that we can’t account for with a good ballistic solver because it is the only thing we cannot say for sure that we actually know. We can use a laser range finder and know the range within +/- 5yds which is not a huge deal. We can use our phone or Kestrel to get all the atmospherics (temperature, barometric pressure, and humidity). With those we we can calculate the deterministic variable of drop. Since we know we don’t carry enough velocity to shoot much beyond 400yds with the light bullets and about 500yds with the better heavy stuff we don’t have to worry much about spin drift or Coriolis. Both are very minimal to imperceptible at those distances. Wind on the other hand makes all the difference in the world and your phone or Kestrel cannot give you a definitive answer as to what the wind is doing, just what the wind is doing exactly where you are.
Winds are like fluids. They ebb and flow. They roll over the ground, speeding up, slowing down, pushing up, pushing down. They swirl. They gust. Winds have gradients that are higher above the ground than they are at the ground. It takes a lot of practice to get a handle on them on a flat range with good indicators like flags and the funny little flowery, spinning things BR guys use. It is even harder to master in the field where your indicators are are natural effects (grass, trees, dust, etc) and perception (feel) or mirage.
There are two ways to ensure success while shooting in the wind. The first, and best, is to shoot in the wind often. Never shy away from the range because it is windy. You will not shoot the little groups you enjoy shooting but it is like I said about shooting groups compared to MoA targets: Who cares? The goal is to make good, centered, repeatable hits on demand. That only happens by shooting in difficult conditions until difficult becomes routine. That will take a lot of practice and a .22LR or a .223 Rem will be a good way to sort it out since the cost of SML bullets and the price you will pay in recoil may be prohibitive. That said, find a way to shoot in the wind as often as you can.
The other approach is to improve your gear. You pick a bullet that offers you the least amount of drift at your maximum range, in the worst conditions you expect. While it is absolutely true you cannot buy skill you can buy bullets that improve your odds despite your skill level. Velocity cannot always best wind despite that common myth. That is what we propose to determine with these WEZ analyses.
We will give ourselves the benefit of the best rifle and load combo we could muster as well as an accurate laser rangefinder. Assume we have a rifle capable of .5MoA groups on demand (although that is only likely with 3-5shot groups, not the 10-shots we tested), an MV with a standard deviation of 7fps (so if you are a Smooth guy you need a Veggie Wad), and we know the range because we own a quality range finder. One gun will have a 275gn MH at 2900fps, one a 300gn MH at 2800fps, and one will have a 344gn BOMB at 2750fps (my personal LR load although it can be pushed faster).
We will rotate these guns between three shooters in medium difficult wind conditions: one a casual shooter (LO confidence) who can guess wind at +/-4mph, one a regular enthusiast who gets out often but doesn’t have a lot of experience or training (MED confidence) who can guess wind at +/-2mph, and one who shoots a lot in competition and/or has very good training (HI confidence) who can call wind at +/- 1mph. This is representative of what I see on SML forums based on what I glean from range reports. Having worked in a gunshop and range for close to 10 years prior to joining the Army I think this is a fair representation of shooters in general.
That said, the greatest enemy for most shooters is they don’t know what they don’t know. I cannot tell you how often I hear some guy asking about shooting deer at 500yds when he has never even shot a piece of paper at 300yds. If you are shooting a .300WM or something similar that is not overly difficult even for a guy without a lot of training but we are shooting low to fairly low BC bullets at slower velocities which means knowing wind effects becomes very critical.
Consider our first scenario where our rifle shoots a 275gn MH (or similar) bullet over 78gn of IMR4198 at roughly 2900fps and produces 1MoA or better groups every time it goes out. We are deer hunting a field we hunt ever year, from a comfortable blind with a solid rest. A good buck steps out of a treeline into the beanfield at 455m/497yds. We know how far it is because we have hunted here for years but we check it with the range finder anyway. We again confirm against our drop chart and see this is the absolute furthest shot we should be taking based on what we got from our phone’s app.
Here’s the rub: our phone says winds are at 5mph (Kestrel’s don’t measure wind inside of a blind) but that is at the local airfield so we take an educated guess based on what we see around us.
Shooter# 2 (Range Regular)
That is a significant difference in success based on ability to read wind. It would stand to reason that spending more time at the range with someone who can teach you would be the best course of action to ensure higher success. The most probable course of action though is that we will try to buy success by improving equipment (probably a bigger scope but shouldn’t be). Let’s say that we take a friend’s advice and try a better bullet even though it will be a little slower and will kick a little more. If we had had the better bullet things would have looked a lot more like this:
300gn MH (or similar) over 73gn H4198 for 2800fps all else equal to the last scenario.
We now have two out of three shooters inside of our 90% threshold by a simple upgrade in a bullet. It was not as apparent in the previous blogs because there was no wind. We also were showing max ranges for each combination before and how each bullet reacted to changes in velocity deviation and form. Now when we combine them and pit them against each other it all comes together.
Finally, lets say that three shooters have known each other for a while and while the two junior shooters have not had the range time to get as good as Shooter #3 but have at least mimicked his choice of gear because of the advantages he says it offers and had it at the onset of this story.
344gn BOMB over 90gn of IMR3031 for 2750fps, all else being equal:
The heavier, harder kicking, higher BC is clearly the champion. It beat out the speed demon 275gn bullet as well as the welter weight 300gn bullet. It didn’t make the average joe a long range expert but it moved him up a lot closer to 70% than the nearly 60% he started out with using the light and fast bullet. The big boy also got there with more velocity and energy and in the hands of the two better shooters could have been used further.
The moral of the story is you cannot buy success but choosing a more appropriate bullet will hedge your bets and increase your odds. There is no substitute for experience and practice when it comes to shooting across fields (or worse yet hills and canyons) and the wind will make that evident. Take what you read, get out from behind your computer, and go hit the range especially if the wind is blowing. Deer season is right around the corner.
