AC­CU­RACY MAT­TERS

Last month we be­gan the process of plot­ting tra­jec­tory. This month we com­plete the process and then use the data, says Mark Camoc­cio

Air Gunner - - CONTENTS -

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!

STA­BIL­ITY

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

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