Last month we began the process of plotting trajectory. This month we complete the process and then use the data, says Mark Camoccio
Mark Camoccio follows up his piece on plotting trajectory and uses the collected data to good effect
Whichever method you pick, the key point is that you need to aim bang on, dead centre of each target every time, and let gravity do the rest. Ideally, have some form of wind indicator downrange too, so that you can gently release well- aimed shots during the calm lulls if necessary. A simple loop of wire with wool or fishing chenille is ideal to show the wind.
Take a few shots at each distance, too, so any erratic flinch is discarded, for example, and won’t be allowed to skew results. Any careful shooting, such as plotting the trajectory, requires concentration and precision. Indeed, I’ve often heard shooters say they can easily hit knock- down, metal silhouette-style targets, yet are no good at shooting at paper. It can be quite demanding, and tired eyes viewing a tiny bullseye can play tricks as we attempt to place pellet on pellet. A good rule of thumb I’ve adhered to over the years is, firstly, over an extended period, to stop shooting if tired, and possibly pack up for another day. Again, this means results will not be skewed. Secondly, base any results over at least a couple of sessions regardless, to discount bad technique or just a bad day. Let’s face it, if we’re basing our whole shooting approach on the results, they need to be properly representative!
When carrying out this exercise in order to check the entire trajectory and collect the data, the idea is to be as technically stable as possible, to make the results meaningful and worthwhile. Therefore, the key is to maintain a super- steady shooting position. Being realistic, that means dispensing with our usual stance and approach, whether that’s sitting, kneeling or standing, and instead adopting an artificially supported position. Unless we are rock solid, and effectively eliminating human error from the equation, it all becomes a pointless exercise. Keep the shooting position as low as possible, so our body and the gun
“Unless we are rock solid, and effectively eliminating human error from the equation, it all becomes a pointless exercise”
can be supported to the maximum. You have to be comfortable, but remember, this isn’t the time for anything clever because we just want to see exactly what the gun can do, and exactly where it shoots at every range. Conduct this exercise from an official range, and you might well have the luxury of a seated position from a bench, and a beanbag or range bag in which to bed in the rifle, but even if shooting from the more supported prone position, I would still advise using a beanbag or padded support of some sort. Those elevated arms in the proper prone position, can still introduce excess movement and wobble, so the idea is to keep ultra- low and let the gun semi- support itself, with the hand cushioning off a beanbag for maximum stability.
PLOTTING AND DATA SHEET
When the exercise is complete, we should have plenty of data to collate; either a continuous line with our shots deviating along it at each marked distance, or a series of targets, shot at each range. Measure the exact drop from the aim point/centre of the target, to the centre of the group, and make a note of the figure. Do this for each target covering each distance, and then plot a graph using all the data. The left side vertical axis shows the point of impact, either plus or minus – in other words, below or above the rifle’s zero. The horizontal axis is marked off in yards for the target distance, and this line also represents the exact point of the rifle’s zero distance.
I have always shot .177 and zeroed my rifle for 35 yards, and this gives me a secondary zero of around 15 yards. The highest point of the trajectory is normally around 20 yards, with the pellet rising sometimes a quarter of an inch, sometimes a third of an inch at this distance, dependant upon the pellet. Look at the graph, and you’ll see that at the maximum HFT distance of 45 yards, my pellet is dropping around 1.25 inches. All these figures relate to my particular gun, using specific mounts, normally Sportsmatch medium specification, and top- quality 8.44 Air Arms Diabolo Field pellets. However, figures and data will still vary slightly gun to gun, and even from one batch of pellets to the next – yes, even with the best pellets.
Ballistic software such as Chairgun is quite brilliant and highly popular, but it is only a guide. There is simply no substitute for actually leaving the house, setting up in the field, and doing some proper research. You won’t regret it. Finally, make up a pocket- sized prompt card to carry around for peace of mind, with all the impact aim points clearly marked. Just having this on you during a competition, is a confidence boost in itself.
Knowing every inch of the trajectory of your favourite rifle really is the key to success, and with an increasing number of small kill zones creeping into more outdoor HFT and FT competitions, thorough preparation is essential. Do your homework, and you’re halfway there.
BELOW: Try to keep yourself and the gun low and supported
BOTTOM RIGHT: We should end up with some nice clear results
RIGHT: Plotting the chart is a good way of learning the arc
BOTTOM LEFT: Ideally, pick a calm day, and keep a check on the breeze