Mark Camoccio tells us why plotting our trajectory is so important
Know the trajectory of your gun! Mark Camoccio explains this basic requirement for accuracy
I’ve been shooting airguns for nearly four decades now – which looks pretty frightening in print! – and from quite an early age, I was hooked into competition shooting. This can be incredibly demanding, and every aspect of our approach ends up being evaluated in a bid for success. However, whichever branch of our great sport you choose to follow, be that hunting, target shooting or fun/casual ‘plinking’ sessions, several principles and methods remain valid throughout.
It’s all about hitting the target, after all, and that means knowing and learning the trajectory of our rifle. It’s a basic requirement that really is fundamental to what follows, yet it still amazes me how many newcomers to the sport have little grasp of what’s required – understandable, I suppose because we just take it for granted.
FAIL TO PREPARE
As with any shooting sport, gravity plays a big part because it pulls down on our projectile. The best airgun pellets are surprisingly efficient in terms of ballistics, and are highly accurate, yet all succumb to external forces. For example, specialist heavy pellets can have an incredibly bowed trajectory, and understanding the effects, and tracking and charting the results that occur downrange has to be the way forward. Several factors influence the trajectory, including the height of the scope mounts; high mounts will increase the height of the sight line above the barrel; low mounts will obviously reduce this, and the pros and cons of such are indeed a complex subject in themselves, perhaps a topic for another day.
Plotting the trajectory needs to be done with a zeroed scope/rifle combination. For the record, I zero at 35 yards with .177 calibre, and 25
yards would be a good starting point in .22, but I’ll deal with choosing a zero distance another time. So, for the purpose of this article, I’m assuming that we have a rifle/scope combination set up and zeroed already, and we just want to plot the trajectory effectively, to know exactly where the pellet’s point of impact is at each distance.
I shoot hunter field target, and I need to know exactly where my pellet lands at targets set from 8 yards right out to 45 yards. Of course, I still need to estimate that distance, but the key piece of preparation is to know how your gun performs, and have it all down on paper. It goes without saying that when taking on live quarry, exactly the same data knowledge is a prerequisite, so it really is a vital early stage.
Any precision work needs still air, and for this reason, indoor ranges are springing up all over the country, where shooters can evaluate their kit unhindered by the elements, but if you have permission to shoot on a piece of land, or more commonly, a club ground, then wait for a super- calm, still day – and then strike!
If the session has to be at the club, then ideally, pick a day when you are likely to be undisturbed because the process does require walking up and down the range to check results. The aim is to shoot a few shots at each distance to see the impact points. Place target boards out at 8 yards – the minimum distance in hunter field target – then at 10 yards, and then 5- yard intervals thereafter, right up to 55 yards. This covers distances used in field target courses, and comfortably any other range at which a 12 ft.lbs. airgun would be effectively shot. Of course, in between distances can be checked too, as required.
It’s easier to run this trajectory check when you are on your own, undisturbed, and you can just settle down and relax. In this instance, you can either put target boards at each distance, or just have one board and keep moving back in five- yard intervals, firing a few shots at each range. Forget about elaborate target designs here because we want to be able to see the shots easily. Just get some white card – cereal packets are ideal – and draw round a coin with a light- coloured marker. Red seems ideal because it’s nice and visible, yet the shots still shows up from a distance. Another simple method is to use a straight line with a side scale. Just shoot at the line at each distance, and keep moving back to each desired distance that needs to be checked. I mark the side scale in inches, but this is more of a guide from the firing line because it obviously makes sense to measure and log the results afterwards.
Next month, we’ll complete this vital exercise, and see what we can do with the data gathered.
“we want to plot the trajectory effectively, to know exactly where the pellet’s point of impact is at each distance”
Pick a calm day with no wind and settle down, undisturbed, for proper evaluation
BOTTOM LEFT: A straight- line target such as this can be used, moving out to each range
TOP LEFT: Use white card for ultrauncluttered, clear results
BELOW: Use club boards if necessary, and place them out at 8 yards, then 10, and then 5-yard intervals