It’s Called Dope

The direction of light and its intensity can change where the target appears to be. Iron sight shooters have held fast to a general rule for many years, “sun up sights up, sun down sights down”. When the sun is bright a distortion will form around the target. This generally causes the shots to print low; the target appears to be higher than it is. When cloud cover exists, there is very little or no distortion. The tendency is to hold closer to where the target really is, which will result in a higher than expected shot. The brighter the sun the bigger the target will seem. How much displacement depends on the brightness of the sun and the distance you are from the target. Training in variable conditions can increase your hit.

ELEVATION and HUMIDITY

We have to evaluate the effect of air density, which produce drag placed upon the bullet in flight. The higher the altitude the thinner the air. Given a zero at a lesser altitude your bullet will print higher when fired in the higher elevation. Humidity is simply the amount of moisture in the air. Moisture in the air places drag on the bullet. The more moisture the more drag which will cause your bullet to print lower. How much displacement depends on how much conditions have changed from those when zeroing, and as usual, how far we are from the target. If you work in an area where the probability exists that you may be deployed at different elevations, you should have zeros calculated for each variation. Barometric pressure normally ranges in the area of 29.0 to 32.0 psi. Decreases in barometric pressure will decrease the density of the air and allow the bullet to impact higher on the target. The following chart illustrates the approximate change of impact from sea level to ten thousand feet, given the rifle was zeroed to point of aim. Point impact at sea level. The chart is also dependent upon shooting match grade ammunition in .308 Winchester caliber at approximately 2600 feet per second.

IMPACT RISE WITH CHANGE OF ELEVATION IN MINUTES OF ANGLE.

The information in this chart is computer generated and generally reliable. However, it does not take the place of actual dope developed by the marksman. Use this information for reference only.

WIND, its DIRECTION and VELOCITY

On the average police shootings, involving rifles, involve distances of less than 80 yards. Within this distance wind affect upon shot placement is very little. Let’s refer to this statistic as our average shot. If these were the only shots we ever had to make, there would be very little reason for a discussion on wind. So we are going to move the target down range and talk about other than average shots. We need to discuss this for two reasons.

a. The potential is there to require such a shot.

b. We still have to hit where we are aiming. At this time it should be obvious that the distance from the target will dictate the amount of adjustment required compensating for given conditions. This is true because the farther you are, the longer the bullet is in flight. The longer the bullet is in flight the more time conditions have to influence its travel. On ranges of known distance the flag method is the system most often used to determine direction and velocity. Flags or windsocks are placed on poles to be up range of the target. The shooter views the flags to determine direction. By calculating the angle of the flag and dividing by a number representing the caliber of the round being fired the shooter can determine velocity. An explanation of this method can be found in most rifle data books. A lot of people use this method, but for the life of me I can’t figure out why. I suppose, like wind reading instrument, taking the flags into account with everything else provides the shooter with more information that can verify their decision. Here are the problems with flags.

A. Flags fly high above the berms; the bullet doesn’t. So generally the wind at the flag is not the condition that will have affect on the bullet flight.

B. Looking at flags across a long range will generally provide you with conflicting information, as wind conditions are seldom consistence over a long distance.

C. Depending on the weight of the flag, the material it’s made of, or the amount of moisture it has collected, the wind will move it differently.

D. Flags do not respond quickly to change.

I’m sure that more rationale in this matter is available, but these are the primary reasons why flags are not my choice. From the tactical shooters perspective whatever you can see moving, between you and your target, is of important. Make sure it’s between you and your target. Don’t fall victim to false indicators. A directional vane on the roof is no indication of what occurring at ground level between buildings. Look for things like flag attached to the side of a house, clothes on a line, hanging plants or flowers, (not the whole hanger, the plant inside) wind chimes, hanging bird houses and feeders, lawn ornaments that twirl in the breeze, even swings sets, water rippling on the surface of a pool, or pond. Wind moves very differently around the buildings. Your favorite radio station may tell you that the wind is out of the West today. This is not an indication that this is the condition where you are. Sometimes wetting your finger and holding it up in the breeze is as good as you are going to get. Incidentally, the cold side will be the way the wind is coming from. For that long shot that we have to hurry up get into position and then are put on hold. Most people in the business have experienced this more than once. While on hold, conditions in the wind have to be monitored. A dominant condition must be determined. Dominant condition is simply that condition that prevails most of the time. Then we look for variations in the conditions. The best way to do this and any other wind analysis is by looking at mirage through a spotting scope. Mirage is simply heat waves reflecting from object. The warmer the day the more mirage you will see. Anyone who has watched a fire has noticed the distortion that develops from the heat. This distortion is what we look for in the scope. When these waves are observed, movement will be identifies. The direction of that movement is the way the wind is blowing at that specific place, at that specific time. Mirage is best captured by focusing on the object you are reading and then turning the scope slightly out of focus. Your ability to see the distortion will improve. You’re looking for movement in the heat waves themselves. Watch the waves bend, to see the affects of the wind and read the wind direction. The best place to read mirage is when you can. Ideally you want to be halfway between you and your target directly in the path the bullet will travel. However, ideal is not what is always available. You may have to improvise, at a different distance, look for a sandbox, automobile, pavement, windows sills, basically anything that is in the sunlight. Watch the waves and observe the changes. Remember that wind is rarely constant. This brings up a critical point. When you dope the wind, you have to shoot the wind. Don’t dope for ten mile an hour wind and then wait for a lull in the breeze to shoot. Guess what? You are going to miss. You must be observant to change and change with the conditions. A marksman who stays in position for an extended period will change sight settings several times. It is not uncommon for competitive shooters, at six hundred yards, to make adjustment four or five times in a twenty-minute string of fire. If the mirage is moving vertically, it is called boiling. This is an indication the wind is moving very slowly or is non-existent. Many people think that this is the time to deliver a shot, it isn’t. This vertical distortion makes the target elongate, appearing higher than it is. This perception increases at greater distances. Most competitive shooters will not launch a round in this condition and to them there is only an X-ring at stake. I would say if competition shooters shy away from this shot it certainly warrants our consideration. Another thing to consider about a boiling mirage is this. If you look at your target and see right to left or left to right movement but can’t really determine wind direction, turn your scope right or left until you see a boiling mirage. That will be the direction the wind is blowing. Watching the mirage move from right to left or left to right is what the marksman is looking for when doping for windage. Generally, when we consider doping for wind, it has to do with moving the bullet from off center, to center. The slant of the mirage’s waves will provide information about velocity as well as direction. The greater the slant the faster the wind. When you see the lines of the mirage horizontal and straight you have a really good wind, usually twenty plus miles per hour. This is an extremely poor condition to deliver a shot in. Also keep in mind that when you have this type of wind, even of lesser velocity, the target will be distorted in the direction the wind is moving. The target will be left, or right, of where you thing it is.

EXAMPLE

If you have bright, sunny, day and distortion surrounds your target, watch the mirage. You will see it elongate the target. If the wind is blowing from left to right you will see the right side of the target get bigger. This area of the target will appear to swell in the direction the mirage is moving. If the swelling of the area appears to pulsate, that means the wind is intermittent. Again, these effects increase with distance. There are some relatively new instruments on the market to measure wind velocity. Here are some things to think about.

A. It tells you wind speed where you are. You really need to know wind speed about halfway between you and your target.

B. The instrument generally reads the highest velocity. It does not provide information on lulls, changes and buildup.

C. It cannot always detect direction of wind.

As a piece of equipment, the wind gauge should be used in conjunction with your observations. Do not use it as an exclusive measurement. Simply factor the information obtained with other information. Your location will be the key factor in determining its usefulness, and sometimes it will be more useful than others will. Where I see this toll at its best is in training. Read the mirage off a location at a midway point down range. Then go down and check it with the instrument See how close you are. Don’t be dismayed to have four or five instruments of the same manufacturer give you many different reading, but they should be consistent with themselves. So learning your dope with the instrument should provide consistency with what you get as a reading and what you see in your scope. Give it a try. As an aside, I have had people tell me, “I don’t have anything downrange I can read”. If this is the case, or if there is some range rule that prohibits placing something their, use a piece of tar paper. For you roofers, this is “felt”, I know, but rifle guys are a technical bunch. I haven’t found anyone yet who will object to placing a piece of tarpaper on the ground, maybe three or four feet square put a little dirt on the edges so it won’t blow away. This will provide you with a common spotting location and is an excellent tool to train people to dope. Judging wind velocity by mirage movement is an art form. Nobody I know of, who is knowledgeable, will tell you it is an exact science or that it has exacting qualities. The ability to read mirage comes with experience. There is just no other way to learn it well enough to make critical shot. The other key factor in doping is knowing your equipment. Just because your department has a thousand dollars invested in a riflescope, doesn’t mean you get a quarter minute click when you turn the adjustment knob. That may be what you are supposed to get, but it rarely is. You will not know until you get out and try it. People who know their equipment know this is true, the rest you will learn soon. When you’re doping, don’t just assume that you made a mistake in application of the dope. Draw a picture of what your read looks like so that it is comparable at another time. Identify reads that are similar. Check to see if the same dope applied consistently. This is how you collect real dope. “I have seen this before, this is what I did, and this is how it works.” This information is priceless to the marksman who needs to make the shot count. You cannot count this information as pure fact. Weather conditions change as well as the condition of your gun and maybe a new lot number of ammunition has been thrown in. Never discount the variables. Look out for false mirage, reflections of mirage itself, and make sure what you are looking at is real. Even long time shooters can be fooled; this is evidence you have to work at your craft. The major reason the tactical shooter should dope from mirage readings is the fact that wind change can be detected immediately.

Suggestions to Improve Your Ability

A. Alter you’re shooting schedule any time you can. Don’t go to the range at the same time of day.

B. Shoot on different ranges whenever possible.

C. Shoot in a variety of weather conditions, don’t just go out on sunny days. A little rain may impress you as to what it will do. Do we still work in the rain?

D. Zeros are funny thing. Many times we shoot from sand bags or other supported positions, rests and bipods and the like, obtain a zero and next time we shoot off something else and wonder why our zero changed. The only place to zero is in the position and conditions you are going to employ in. Example; I shoot three clicks difference from standing to sitting, two clicks different from sitting to prone, and two clicks different from sitting to supported kneeling. What I do off a bench or bipod is two to five clicks off from all other positions. Check it out.

E. Make sure you record, keep and review you data. Constantly compare your new efforts with previous recordings. By review you will learn things about your rifle. Change with it and rebarrel it when it’s time.

Good Shooting

Bill Porter

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