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Long Range Shooting & Hunting - Page 3

Rifle Inaccuracy

Earlier we discussed the building of an accurate long-range rifle but one of the most common reasons for missing a target or for poor grouping at long-range is a rifle that just isn't up to snuff. Accuracy in this game seems to be like many temporal things in life, you just can't get enough of it. Actually, we can divide the accuracy problem into two distinct areas, rifle inaccuracy and ammunition inaccuracy.

The heavier a rifle is, generally speaking, the more accurate it is. We can't expect an eight pound sporter to shoot as well as a 40 pound bench gun. The shooter must decide first, I believe, when building or modifying a rifle for long-range shooting, how much he wants it to weigh when finished. If he plans to walk around with it at all, then probably a 10-15 pound rifle is the maximum weight. It will most likely be closer to 10 pounds, too. If though, he plans to shoot it exclusively from a bench or stand, weight is not much of a consideration. As we said, heavier is better (at least in the accurate gun world) because the component parts are bigger and stiffer. Also, a heavier rifle will have much less recoil. On a lighter weight rifle, a muzzle brake will reduce recoil considerably though.

The rifle must be built around a potentially accurate action with a good trigger. As I mentioned before, I like the custom actions but something like a Remington 700 will work well. If the action will be bedded conventionally then the amount of weight in the barrel must be looked at closely. It is quite possible to bend a commercial magazine-type rifle receiver by hanging 10-15 pounds of barrel from it. Again, the big single shot custom actions are the best for this application. My 338-378 Weatherby Mag, which is shown in the picture, is an example of a big action. It is a single shot and is made from 2" diameter steel. The barrel threads into the action for almost two inches, too. An action like this will handle a big barrel. Use big actions for big barrels.

An alternative to the big action - big barrel philosophy is the use of a barrel bedding block. The 300 Weatherby in the photograph is built on an unsleeved Remington 700 action converted to single shot with a Davidson ramp. The barrel is 1.450" in diameter for 30". It is actually larger in diameter than the action. The barrel though, is epoxied into the block with the action and remainder of the barrel floating. In this example the barrel is glued but some rifles use a split block with the barrel clamped in the block.

If you are going to put weight into a rifle, the barrel is the best place to do it. The larger a barrel is in diameter the stiffer it is. Barrel stiffness or rigidity increases with the fourth power of its diameter. This means that a 2" diameter barrel is 16 times stiffer than one of 1" diameter since 2^4 is 16.

Conversely, barrel stiffness decreases with the third power of its length. As an example, a 30 inch long 30 caliber barrel with a 1" thread shank and 1.450" in diameter its full length is much less stiff than the same barrel glued into a block. If we compare it to the same barrel mounted in an 8" long block with a 1/2" space between the block and action, we are comparing essentially a 29" long barrel to one 20.5" long. In this example the blocked barrel is 2.8 times stiffer. That's right, the difference in rigidity is almost 3 times in favor of the shorter one. Stiffness means, potentially, more accuracy.

The points here to remember are that a barrel increases in rigidity with the fourth power of its diameter and decreases with the third power of its length.

In the big magnum cartridges burning shovels-full of slow burning powder, barrel length means bullet velocity. Bullet velocity means less wind drift and less bullet drop. Decreasing bullet drop and drift probably means increased accuracy but extra barrel length can mean decreased accuracy because of decreased rigidity and an increase in fouling inside the barrel. To some extent, blocking the barrel lets you have your cake and eat it, too.

The rifle stock must be one that is easy to control on the sandbags and be large enough to support the weight of the barreled action. Laminated wood stocks are both pretty and functional or there are a couple of good fiberglass patterns that work well with these big guns. The weight of the stock should be distributed so that the rifle is not muzzle heavy due to a big barrel. Some have added weight to the butt of the stock to counter this tendency.

The above few paragraphs highlight some of the important areas to look at in modifying or rebuilding a long-range rifle. We won't discuss cartridges, as that was covered pretty well in the beginning of this article and seems to be a topic of ongoing discussion in most firearm publications. A magnum cartridge of some persuasion is the best way to go.

The rifle may be very capable in the accuracy department but is being fed the wrong ammunition. Bullets are extremely important. They must be true match quality bullets if any degree of accuracy is expected. As an example of bullet quality, the 300 Weatherby in the photo is capable of sub .200" groups at 100 yards with 220 grain Sierra Match Kings seated to the correct depth. With a 200 grain soft point hunting bullet from another manufacturer, the very best it will do is 3/4" groups. Shooting groups at 100 yards is not always the best test for accuracy with one of these rifles but this example indicates the importance of best quality bullets.

The cartridge must also be loaded with the correct amount of the right powder. For most shooters the fun part of building a new rifle or rebarreling, is load development. I turn the case necks for my serious long-range rifles. I feel that it does help accuracy and as I said, we need all we can get. Pick a good quality bullet first and then find a powder that delivers maximum velocity with minimum velocity variation and good accuracy. Don't do all of your initial testing at 100 yards either. Usually a load that performs well at 100 yards will also do well farther out, but not always. Shooting paper at 1000 yards can be an eye opening experience with surprises in store. Although not a long-range rifle, I had a heavy varmint 6PPC that shot about the same size groups at 200 yards as it did at 100 yards. Groups in the 3's and 4's with an occasional one in the 2's won't get you much in 100 yard matches but at 200 yards they look mighty good. Why this barrel behaved that way I can't say but the proof is on my targets.

Vertical grouping at long-range may be an indication of pressure problems in the load. Changing the charge weight or powder type may cure it, as might trying another bullet weight or seating depth. It could also be an indication of high velocity variation with that charge. We will discuss an example of extreme spreads in velocity a bit later.

Range Errors

Another possible reason for missing a shot way out there is an incorrect range reading. The Barr & Stroud rangefinders really are the only optical rangefinder available to accurately determine distances. They can go out of adjustment though. The farther out an object is, the less accurate these rangefinders are too, and the more difficult it is to correctly bring the images into coincidence. Because it has a wider baseline, the 500 yard model is more accurate than the 250 yard model for distances beyond 500 yards.

I missed a shot at a nice bull elk once because of an error in reading the range to him. I was hunting in the Bitterroot Mountains and there was about 6" of snow on the ground at my elevation with even more in the higher mountains near the pass. The elk had moved down because of it, and they were relatively easy to spot across the big canyons. I looked over about 40 cows that morning but hadn't seen a bull other than a spike about 2 miles away. I soon saw another cow and was looking at her through my 10x50 binoculars when, lo and behold, I finally found a bull.

I quickly set up my 250 model Barr & Stroud rangefinder and found the bull in the field of view. He was pawing through the snow for grass in a small opening in the trees of about an acre or so in size. Earlier, at home, I had checked the calibration of the range finder on a power pole a surveyor measured for me at 999 yards. It was right on the mark, and after checking it I left the rangefinder set on 1000 yards. When I put the Barr & Stroud on the bull, he was moving a little as he fed. It looked to me like he was exactly 1000 yards away; I hadn't adjusted the rangefinder at all. Great, I thought; my scope was already set for 1000 yards, too. I was sure I'd soon have a few hundred pounds of excellent meat on the ground.

I found the elk in my 24x scope and launched a 338 caliber bullet at him from the 338-378. Well, to make a longer story short, I missed. I missed with my second shot too. He didn't stay in the open after that and with a long face I started putting my equipment away. To be sure I missed, I walked over where he had been. If I had hit him it would have been very clear in the fresh snow. Walking back I wondered why I had missed. Well, it turned out that I'd made an error reading the range to the bull and learned a lesson, I hope. I rechecked the range to a bush that was right where the bull had been standing. It read 960 yards. I had been fooled into thinking the bull was 1000 yards away because he was moving a little when I ranged him and the rangefinder was already set close to what he actually was.

With the bullet and load I was using, the difference in drop between a 960 yard zero and one for 1000 yards is about 25". I had shot right over his back. For those not familiar with the Barr & Stroud system, it might be hard to visualize how the images are displayed in the eyepiece. Believe me though, it can happen. Take the extra time required to accurately read the range to any target.

Wind Drift

That old tricky wind has always been one of the bigger reasons for inaccuracy at extended ranges. When target shooting at long-range, a horizontal dispersion of the shots is a sure indicator that the wind was playing out its hand. It is difficult to judge wind way out there. Mirage is a good indicator and sometimes the only one. I remember looking across a big canyon once while there were a few small cumulus clouds between me and the other side. It didn't seem like the wind was blowing at all, but those clouds were drifting very slowly left to right. There have been other times when I was hunting and it was snowing. Snow just might be the best wind flag there is. It is easy to see and probably extends all the way to the target. Hopefully it isn't obscuring the target too much.

If mirage is the only indicator of wind direction it can be difficult to determine exactly which direction the wind is coming from. Usually we can see if it is running from the right or left or boiling, but that is about all. Here is a little tip to determine exactly what direction the wind is blowing from. Looking through a spotting scope on a tripod, rotate the scope around the clock until the mirage is boiling. When it's boiling you know that the wind is coming either directly at you or blowing away; it should be easy to determine which. Out on the plains country this can be a big help.

With my 338-378 Weatherby load using the original experimental 320 grain Sierra, a 10 MPH direct cross wind blowing the full distance to the target will drift the bullet about 43 inches at 1000 yards. At 500 yards it is less than 10 inches. Other cartridges and bullets will probably drift more, so the wind is definitely a factor. It is for this reason that the heavy bullets for a particular caliber are preferred. The heavier examples have a higher ballistic coefficient and as a result will drift less in the wind. A lighter bullet may drop less, but it will also probably drift more in a breeze. Using the rangefinding and scope adjusting techniques we have discussed in the earlier segments of this article, eliminates most of the problems associated with bullet drop. All this boils down to the fact that it is much easier to determine the distance to an object with a rangefinder and compensate for the bullet drop at that distance than it is to guess how hard the wind is blowing.

For example, if we compare two 30 caliber bullets fired from a long barreled 300 Weatherby our point will be shown. The 168 grain Sierra Match King has a ballistic coefficient of .475 and can be driven at close to 3300 fps in the big Weatherby. The 220 grain Sierra Match King has a ballistic coefficient of .655 according to Sierra. In my experience the BC for the 220 grain bullet is closer to .640 and I use this figure for my drop charts. To see how the wind drift compares, I ran these numbers through a Tioga Engineering ballistics program that computes drop and drift for a 10 mph breeze.

At a muzzle velocity of 3300 fps the 168 grain bullet will blow about 15.5 inches at 500 yards, 38 inches at 750 yards, 75.5 inches at 1000 yards, 130.5 inches at 1250 yards and 206 inches at 1500 yards. The 220 grain Match King will drift 13 inches at 500 yards, 31.5 at 750 yards, 61.5 at 1000 yards, 103 inches at 1250 yards, and 160 inches at 1500 yards. At every yardage the drift for the same 10 mph wind is less for the higher ballistic coefficient 220 grain bullet. The drop for the 168 is less though. About 11.4 inches less at 500 yards, 23.2 inches at 750 yards, 34.7 at 1000 yards, 32.4 inches at 1250 yards (its starting to catch up now) and at 1500 yards, they are just about even (1 inch more for the 220 grain).

If anything, this example is skewed in favor of the 168 grain bullet for two reasons. First we used Sierra's ballistic coefficient figure for the 168 grain bullet but lowered theirs for the 220 grain bullet. Secondly, going with a 400 fps difference between the two bullets is being a bit generous. In reality, the difference would probably not be quite that great. Giving the 168 grain Match King a 3300 fps muzzle velocity is being a little optimistic.

The point is, a higher BC from a heavier bullet of the same basic shape means less wind drift. It also means more drop, but if we know the exact range to the target, actual drop is not as important as wind drift is. Hence, the high BC bullet is the best choice, provided it is also accurate.

Using Incorrect Velocity

As we mentioned earlier, using the wrong velocity on the drop chart can lead to misses. There are several reasons why the actual muzzle velocities in the field from a proven rifle may be different than expected. Changes in powder lots or types or even primers can have an effect on velocity. They might not always cause a big change, but they can sometimes. Another possible reason is throat erosion. Usually velocity will decrease as a throat moves forward. A load chronographed early in a barrel's life may not produce the same velocity several hundred rounds later.

Chronographing and long-range accuracy testing of a 340 Weatherby.
Notice the chronograph screens in front of the bench.

Changes in temperature can also affect velocities. With my 338-378 I have checked the velocities for my load from about 30 degrees up to 85 degrees. As an example of what temperature changes can do I'm listing what I found my velocities to be at different temperatures. The powder is IMR 5010 ignited by Federal 215 primers, and the bullet is the experimental 320 grain Sierra Match King. At 29 degrees it averaged 2696 and 2722 fps, at 40 degrees 2717 and 2720 fps, at 50 degrees 2735 fps, 2774 fps at 60 degrees, 2796 fps at 76 degrees and 2802 and 2784 fps at 82 degrees. The trend is obviously an increase in velocity as the temperature goes up. The difference in velocity from the high 20's to the low 80's is about 100 fps. That is easily enough to cause a miss at extended ranges if the wrong velocity is used on the drop chart. With this load, a change in velocity of just 50 fps translates into a difference in drop at 1000 yards of about 12 inches and at 1500 yards it is almost 3 feet.

Other cartridges and powders might show a much different picture, but the general trend is for velocities to go up with temperature. It's best to know what the load in your rifle is producing for the conditions you plan to shoot in.

Ballistic Coefficient Errors

As an example of using the wrong ballistic coefficient, if we use the Sierra 338 Match King in the 338-378 Weatherby and compare C1 ballistic coefficients of .775 and .825 (.050 difference) we find the difference in drop is 7 inches at 1000 yards and 33 inches at 1500 yards. This bullet actually has a BC of about .800.

As we mentioned earlier, ballistic coefficient changes with velocity. When shooting over a long distance the bullet will go through several different velocity ranges. The best way to know where the bullet will hit is to take it out and fire at many distances. It's fun, too. I frequently take my equipment out into the mountains near my home and shoot at rocks or stumps or bears way out there and compare actual MOA scope corrections to those indicated by the computer printout. By doing so, I can fine-tune my charts for the existing conditions. Coordinating scope clicks with the rangefinder also insures correct scope settings even if rangefinder is out of calibration or the scopes click value is not what it is supposed to be.

Scope Adjustments

Earlier I emphasized the importance of knowing the exact click value of the particular scope being used. Most manufacturers design their adjustments to have a nominal one quarter minute of angle adjustment per click. The problem comes in, however, when the wrong definition of minute of angle is used. One minute of angle at 100 yards is 1.047". This value is very close to exactly one whole inch, so most people round it to 1.000". Some of the manufacturers do, too, although they will state otherwise in product literature. Using true MOA, one quarter minute is .262" at 100 yards, not .250".

The small difference between .250" and .262" may not seem very great, and it isn't at 100 yards. The problem manifests itself, though, when many clicks are dialed into a scope for long-range use. With a 100 yards zero and then dialing in 25 minutes of adjustment for a 1000 zero, 100 clicks are spun into the scope. The difference between one quarter MOA and one quarter inch is .012" at 100 yards. At 1000 yards the difference is .120" or almost 1/8 inch per click. If we multiply that .120" times 100 clicks, the error is now translated into a full 12" at 1000 yards. That is too much built in error. If we know exactly how much the clicks of the scope being used are worth however, we can make adjustments to the MOA correction needed.

When discussing scope adjustments, we have stated that most shooters base their drop charts on a 100 yard zero. This does not mean however that the rifle cannot be zeroed at a farther range and the impact point checked against the drop chart. This is in fact a very good idea. I'm sure that not all 100 yard ranges are exactly 100 yards. In fact, I know of one that is exactly 100 meters but most shooters using that range assume that is 100 yards. Experience in the field, firing at targets and paper at long-range, is the best way to learn where a rifle and load will shoot.

Shooting Uphill and Downhill

I can only recall one important shot that I have missed at long-range because of the angle to the target. Again I missed a nice bull elk because of it, and this is the tale that I started this trouble shooting section with.

The bull soon wandered off through the brush, and it was obvious that he wasn't hit. We could see him moving in and out of the alders for about an hour and his only interest was in eating.

The next morning we hiked up and found the exact spot in which the bull had been standing when I shot. Elk hair was scattered on top of the snow but we saw no blood. I examined the alders a few feet behind his tracks and found where the bullet had clipped off a few branches. The pruned limbs were just at the height of an elk's back. I didn't fudge quite right. Had I put one or two less clicks into the scope, I would have taken him.

Well, we learn from our mistakes, sometimes more than from our successes. The point is, shooting at a steep angle can be a bit tricky. A 20 degree angle may not seem very steep, but believe me, it is and the same thing can happen downhill. Earlier we discussed the math involved in uphill/downhill trajectory calculations in detail. The farther away the target is, the more effect the angle has on actual drop.

We can see that there are likely reasons why a shot does not go where it was intended. As we just mentioned angled shooting may be a cause as can the wind. Aside from these two possibilities and rifle inaccuracy, the reason is probably related to a change in bullet velocity, using the incorrect ballistic coefficient, using an incorrect scope click value in calculating MOA corrections, or an error in range measurement.

Ethical?

A few have been critical of long-range big game hunting and one or two have just flat out refused to believe that such nonsense could even be true. To those who don't believe, I can only say it is true and very possible to hunt at long-range. The heavy 1000 yard target-type rifles used while hunting are capable of tremendous accuracy. A look at some of the record groups, that have been fired during 1000 yard benchrest competition can be seen on another part of our web site, is impressive. Five shot groups under 4 inches are quite possible at 1000 yards.

For those who think it is an unethical way to hunt, I have to wonder if they think hunting of any sort is morally right other than "conventional" hunting? I don't criticize other forms of big game hunting such as archery, handgun hunting, muzzle loaders, shotgun slugs and buckshot, baiting, or hunting with dogs. So why do they? I can guarantee that my long-range rifles are far more accurate at any range than any of the weapons I just mentioned. The fact that I choose to hunt using the methods my articles have described, with some judgement thrown in, does not make me any less of a sportsman than conventional hunters or those using the other methods I mentioned.

To those who would like to hunt at long-range but have yet to do so, I would like to offer the following. If you want to hunt at long-range, don't go about it in a half prepared way. Buy the necessary equipment and practice with it on inanimate objects a lot before attempting to go hunting. Learn your equipment and your own limitations and don't go past them while hunting. It can be fun, frustrating and rewarding. If I have made any contribution to your success then we both will have gained.

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