Gurus Grumbles
"Maths" for sight alterations.
Do the Maths for sight alterations.. I saw what prompted this grumble recently when a shooter took five shots to hit the vee bull from way out in the rings on the target. You need to understand the maths of the movement on the sight, and be very aware of the target dimensions according to standard shooting rules. (Speaking of the rules, how many of you have a copy of the SSR?s?) In imperial measure, a rear sight, if it is half minute clicks moves the projectile across the target in minutes of angle. Ie, One minute, which is TWO clicks on a half minute sight, will move you one inch at 100 yards. This means TWO clicks at 300 yards moves the projectile three inches. Four inches at 400, five inches at 500, and so on back to 1,000 yards. The measurement across the 300 bullseye diameter is five and a half inches, which means that on the sight the distance is a shade under TWO full minutes. This also means it takes almost four clicks on your half minute Central sight to place your shot from each diameter line across the bulls eye from line to line! If you are using third minutes on the rear sight it will take five clicks. The current vee bull on a 300 target is two and three quarters of an inch, so it takes almost a full minute to transverse the lines on the vee bull. IE two clicks will move you from one side to the other. At 500 recently, my first sighter shot, (with an incorrect wind arm zero Note,) registered a magpie way out at 9 o?clock smack on the waterline. This shot landed, (I worked out by studying the lines on the target) to be getting close to 25 Inches from the centre of the target. I knew the bull dimension was 10 and a « inches which gave a closer idea of the shot position measurement, so I moved the wind arm on my half minute sight four full points (8 clicks) and shot a 2 o?clock vee bull for the second sighter. It really is important to have a very good idea of the target dimensions when working out a sight correction. You can save a lot of angst if the measurements are known. It is also extremely critical with wind judgement if you know how far the sight moves the bullet on the target. I was marking a target last Saturday, and one of the shooters had a problem in that the first sighter was way out in the outer ring. It took four shots before the bullseye was reached, and this can be crucial in a competition. The first sighter was way out at four o?clock in the outer ring, the second sighter was about 8 inches further in, and so on until the shot hole reached the bulls eye. If the shooter was happy with the shots, then the rest was mathematics, based on the target dimensions. Let me tell you that from the edge of the target to the vee bull is at least seven minutes. This could have saved the shooter 3 shots fining out, and there is no difference between an inner four on the right, and an inner four on the left. They both still count four, but at least something was done more accurately about the shot position when you moved the sight on a more educated decision. Learn the dimensions of your target, it can come in very handy. I had an occasion a long time ago when I was shooting in a shoot off at 800 yards, trying to get my shots away really fast before an approaching storm. I had both sighters and three shots away, when a howling gale hit the range. The flags looked like they were starched! I was lucky as it turned out, when the shooter on my right let one away just as the wind hit us. It landed in the outer ring of my target at 3 o?clock. I was stymied, wondering what the hell was out there on the wind arm, when it hit me like a ton of bricks?.. I moved four points left on the outer already on my plate, aimed at the next door target, fired, and shot a hole fair in the middle!! I moved a half minute further left, did the same thing again and finished out my shoot off, with a clean aggregate. This has zip to do with dimensions, but I gave myself ten for thought! The guy on my right went on to win the Queens that day, he just shook his head when I told him what I had done about 15 years later! Shooting is a mind sport, how well you shoot is directly related to how well you think, but it does give you an advantage if you can do the Maths! Guru