Shooting uphill or downhill. Koos Barnard

[Koos Barnard]

Dagsê
Ek weet baie mense lees nie tydskrifte nie. Hier is 'n praktiese toets oor berg-op en berg-af skiet wat ek vroeër vanjaar gedoen het. Die artikel is in Magnum gepubliseer. Die res van die foto's en byskrifte verskyn in die volgende post. Die foto waar ek sit en skiet is hoe al die toetse gedoen is... vanaf 'n veldrus soos wat ek gebruik as ek jag. Die hoek waarteen ek skiet is ongeveer 18-grade. OP die tweede foto is die berg waarop die teiken staangemaak is: reg bo-op die kruin.

Shooting uphill and downhill
By Koos Barnard

A conundrum or easy as pie?

What forces work on a bullet when we shoot uphill or downhill? How do we adjust our aim; do we aim lower with downhill shots and higher when shooting uphill? And do we take both the distance to the target and the up/down degree of angle into account or just the distance?

Gregor Woods wrote in Gallery (July/Aug 2024): “The subject of aim elevation when shooting up or down steep slopes is often misunderstood. Many believe that you should aim higher when shooting uphill and lower when shooting downhill. Not so. You should aim higher in both cases.”

That is correct but what many people forget or simply miss because they don’t read properly is that you only aim higher when your target is further away than your rifle’s horizontal zeroing distance. If your rifle is zeroed at 200m and the animal is 260m away (measured uphill or downhill), just compensate as you normally would… aim slightly higher.

But how do you compensate when your rifle is zeroed at 200m and you shoot downhill or uphill at a measured 200m? Will your shots land high or low? Much confusion exists about this matter but by applying some basic physics, we’ll get to the truth.

Gravity exerts maximum influence on a bullet when its path is level or perpendicular to the earth’s pull. It is the horizontal distance to the target that matters. When the line-of-sight measurement down or up a slope to a target is 200m, the horizontal distance between shooter and target will be slightly shorter.

Thus, when shooting uphill or downhill, less force is exerted on the bullet, therefore it will hit slightly higher than when fired over a horizontal distance of 200m. Please note though, bullets will only hit noticeably higher at longer ranges and when fired at very steep angles.

Unfortunately, many hunters forget to bring distance into the equation, they only remember the “aim higher” bit and believe that even the slightest deviation from the horizontal will affect a bullet’s trajectory. Just recently a hunter told me how he missed a mountain reedbuck ram’s head at 110m while shooting slightly downhill. He aimed higher (at the base of the horns) and missed high – his rifle was zeroed at 150m.

Another mistake hunters make, is to totally overestimate angles. I did too; the angles to a treetop and hilltop which I respectively estimated at 25º and 30º turned out to be 13º and 18º.

To accurately determine up/down angles an inclinometer is needed, something most modern-day rangefinders are fitted with. They not only give you the correct angle but also the true ballistic range (TBR) which is the horizontal distance between you and the target. And remember, it is the true ballistic range to the target that matters, causing bullets to print slightly higher when fired at upward/downward angles.

If your rangefinder doesn’t have a TBR function you can work it out once you have the angle, but that is quite difficult and require having the corresponding cosine value. Fortunately, experts at the FTW Ranch in Texas who run marksmanship courses have done that and I reproduce their findings here (see table). For instance, when shooting at a 5º angle you have to aim/compensate for a distance that equals 99% of the measured distance. At 15º you aim for a distance equaling 96% of the measured distance and at a 30º angle for 87% of the measured distance.

Now, the longer the distance and the steeper the angle the more pronounced the effect. At 300m and shooting up/down at a 30º angle, you need to aim as if the animal is only 261m away.

Rest assured though, at the angles and distances average hunters normally shoot at (up to 16º up/down and out to 300m) there is no need to worry about the influence that inclines might have on bullet point of impact if you go for body shots. You only need to consider the measured distance.

To see for myself whether shooting up or down slopes have any noticeable influence on bullet point of impact at average hunting distances, I ran a number of tests on a Karoo farm. With my wife as helper, we looked for a suitable mountain but it was hard finding one high and steep enough. We battled to get slopes measuring steeper than 20º where I would be able to shoot beyond 200m. On extremely steep slopes (30º+) I could only get maximum distances of less than 100m.

While measuring slopes with my rangefinder, I realized just how extreme 25º inclines are. I am now convinced that uphill/downhill shots in South Africa only very rarely exceed 20º. The angles of slopes local hunters encounter, most probably fall between 13º and 20º. I also discovered that slopes look much steeper than they are when you look downwards from the tops of mountains.

My tests cannot be regarded as scientific, they are reality tests. I did what hunters normally do; arrive at the farm in the afternoon, confirm the rifle’s zero and hunt the next day (only difference, I shot at paper targets). To keep things realistic, all my shooting was done from the sitting position while using a camera tripod as rifle rest.

I ran the tests at three different locations on the property. At the first I used my .223 Rem to fire two, two-shot groups from 100m at a bull’s-eye target – first over level ground and then downhill at 18º. Then I fired a two-shot group from 200m over level ground, and another from the same distance but downhill at a 13º angle (aiming at the bottom edge of the target). All shots were fired in sunny weather with a light breeze blowing from right to left. In both cases the bullets virtually had the same point of impact, no matter the angle (see picture).

At the second location I was hoping to get at least 250m at a 20º angle but we only got 238m at 18º. To minimize the climbing I used two targets, one was set up at the foot of the mountain and the other right at the top in front of two sturdy ghwarrie bushes (to prevent the bullets from travelling over the horizon). I used my .270 Win loaded with 110gr V-Max bullets.

It was overcast at sunrise so we waited for the clouds to clear and once at the top of the mountain (at 9 a.m.) I fired two shots at the downhill target using my 250m zero. As expected, the bullets struck above point of aim but slightly higher than anticipated.

Thirty minutes later I fired uphill, but shooting at an 18º angle was uncomfortable and I pulled the second shot, so I fired a third. This time the bullets struck even higher (8cm above point of aim). Using the same uphill target I then fired a two-shot group at it over level ground from 238m, again using the 250m zero. By then clouds had moved in again and it was totally overcast. To my surprise the shots landed exactly at point of aim.

Later that day, after the clouds had cleared, I fired three shots at 238m over level ground at a fresh target. Surprise! Under the sunny conditions they landed 4cm high – at exactly the same height as when I fired downhill (see picture).
The only explanation I can think of for those high uphill shots is parallax error and for the low shots over level ground, the change in lighting conditions due to the cloud cover.

I have experienced the same phenomenon before. During a recent shooting competition, I checked my rifle’s zero at 8 a.m. under overcast skies but later that morning in bright sunshine, my shots landed 10cm high on a springbuck target at 300m. Several competitors experienced the same problem. Changing light conditions cause very slight optical illusions – we see the target slightly differently, and aim accordingly, resulting in a changed point of impact.

Discarding the two low shots fired under overcast skies but including the pulled uphill shot, the combined 8-shot group’s vertical dispersion measured 6.5cm and the horizontal 9.5cm. Include the two low shots and the vertical dispersion stretches to 11cm. I extrapolated the shots to an impala target and even when taking the low shots into account, the 10-shot group falls comfortably within the heart/lung area (see picture).

The next location allowed me to fire from 150m at an 18º angle, from 121m at 20º and from 133m at 17º. I used my .223 Rem again, zeroed at 150m, and fired all the shots at a life-size target of a mountain reedbuck. To make aiming easier, I stuck a white-coloured heart to the vital area. The first two shots were taken from 150m over level ground and the next two from 133m downhill at 17º (being slightly out of breath, I pulled the first shot badly to the left). Next, I fired two shots from 150m at 18º downhill. The downhill shots were followed up with one shot uphill from 121m at 20º and finally two shots uphill from 150m at 18º.

The group size (excluding the flyer) was 3.5cm x 3.7cm. Include the pulled shot and the horizontal dispersion stretched from 3.5cm to 6.5cm. As you can see from the picture the difference in point of impact is way too small to worry about. The grouping is still smaller than “minute-of-springbuck-brain”.

To conclude: Whether shooting uphill or downhill you need to aim higher if your target is further away than your rifle’s horizontal zeroing distance. However, due to the true ballistic range effect your compensation would be less than you thought necessary. For general hunting and at angles up to 20º, compensate as you normally would when shooting over level ground. The up/down angles we normally shoot at in South Africa are not steep enough to worry about. It’s basically at 300m and beyond, and at angles exceeding 25º, that you really need to pay attention to adjustments.

Happy hunting!

True ballistic range effect table when shooting uphill or downhill.
Data courtesy of FTW Ranch’s Sportsman’s All-weather All-terrain Marksmanship courses.

Angle in degrees True ballistic range to consider
5º 90% of measured distance uphill/downhill
10º 98% of measured distance "
15º 96% of measured distance "
20 º 94% of measured distance "
25 º 91% of measured distance "
30 º 87% of measured distance "
35 º 82% of measured distance "
40 º 77% of measured distance "
45 º 70% of measured distance "
50 º 64% of measured distance "
55 º 57% of measured distance "
60 º 50% of measured distance "

[Koos Barnard]

HIer is drie foto's, die vierde in die volgende post.

Die eerste foto toon die resultate van die berg-op en berg-af op 238m. Asook die skote op horisontale lyn oor dieselfde afstand.
Die tweede foto is van die ekstrapolasie van al die skote op 'n rooibokteiken. Let wel, al die skote val in die hart/longarea.

Die derde foto is van die ribbok en die skote op verskillende afstande en verskillende hoeke op redelike kortafstand.

[Koos Barnard]

Hierdie foto toon die toetse met die .223 op 100 en 200m oor gelyk grond en berg-af. MEt die 200m-skote het ek vir die onderkant van die wit sirkel gemik.
Onder normale jagomstandighede en normale afstande (onder 300m) is dit nie nodig om jou te veel te bekommer oor die helling waarteen jy skiet nie.

[partner]

Baie Interessant Koos. Baie Dankies.

[Frikkie Coetzee]

Koos. Ek dink jou gevolgtrekkings is nie korrek nie en maak dinge nog meer deurmekaar.

Opdraand en afdraand gaan jy altyd moet LAER mik as vir dieselfde gemete afstand in n horisontale vlak. Gregor Woods se stelling is verkeerd.

Dit is omdat jou ballistiese afstand verminder hoe skerper die hoek waarteen jy skiet.

Jou eie toetse hierbo wys dit vir jou.

In kort. Se jou geweer is ingestel op 300m op n 0 grade vlak en jy skiet dieselfde afstand teen n 30grade hoek op of afdraend gaan jou POI altyd hoer wees omdat jou ballistiese afstand minder is.

Op n 6.5x47 met n 130gr Hornady ELDM sal jou 4.5moa teenoor 3.5 moa wees.

Jy moet dus in beide gevalle LAER mik of stel. Nie hoër nie.

Of dit n praktiese verskil maak is vir elke skut om self oor te besluit. Vir my is 1moa op 300m redelik baie. Dit is sowat 87mm op 300m.

Jou gevolgtrekking se eerste sin is n oksimoroon. As jy verder skiet as jou geweer se 0 afstand gaan jy altyd laag skiet.

Ander stelling wat jy maak is dat jy HOËR skiet in helder sonlig teenoor wanneer dit bewolk was. In Bisley is daar n gesegde. Lights UP, sights UP. Lights down, sights down. Die verskil met n 7mm RSAUM op 900m met n 184gr Berger hybrid teen 2900fps is die verskil selfde meer as n .25 of .50moa.

Ek dink daar is n ander rede vir wat jy ervaar het. Soos die dag warmer raak en jou ammunisie warmer word en as jy dalk met n skoon loop begin het die oggend, is dit meer waarskynlik dat jou spoed toegeneem het en jy nou hoër skiet eerder as die suiwer effek van sonlig.

Kan ek voorstel dat jy die artikel se gevolgtrekkings heroorweeg.

[TFDADD]

In hierdie plasing word die volgende vermeld:

If the shot angle was 40 degrees and the target was at 300 yards, we just multiplied 300 yards by 0.77 and aimed like we were shooting at 231 yards.

Sien tabel in die vermelde plasing hierbo.

Dit stem ooreen met wat Frikkie hierna sê:

by Frikkie Coetzee » 24 Dec 2025 05:47

Opdraand en afdraand gaan jy altyd moet LAER mik as vir dieselfde gemete afstand in n horisontale vlak. Gregor Woods se stelling is verkeerd.

[Koos Barnard]

Koos. Ek dink jou gevolgtrekkings is nie korrek nie en maak dinge nog meer deurmekaar.

Opdraand en afdraand gaan jy altyd moet LAER mik as vir dieselfde gemete afstand in n horisontale vlak. Gregor Woods se stelling is verkeerd.

Dit is omdat jou ballistiese afstand verminder hoe skerper die hoek waarteen jy skiet.

Jou eie toetse hierbo wys dit vir jou.

In kort. Se jou geweer is ingestel op 300m op n 0 grade vlak en jy skiet dieselfde afstand teen n 30grade hoek op of afdraend gaan jou POI altyd hoer wees omdat jou ballistiese afstand minder is.

Op n 6.5x47 met n 130gr Hornady ELDM sal jou 4.5moa teenoor 3.5 moa wees.

Jy moet dus in beide gevalle LAER mik of stel. Nie hoër nie.

Of dit n praktiese verskil maak is vir elke skut om self oor te besluit. Vir my is 1moa op 300m redelik baie. Dit is sowat 87mm op 300m.

Jou gevolgtrekking se eerste sin is n oksimoroon. As jy verder skiet as jou geweer se 0 afstand gaan jy altyd laag skiet.

Ander stelling wat jy maak is dat jy HOËR skiet in helder sonlig teenoor wanneer dit bewolk was. In Bisley is daar n gesegde. Lights UP, sights UP. Lights down, sights down. Die verskil met n 7mm RSAUM op 900m met n 184gr Berger hybrid teen 2900fps is die verskil selfde meer as n .25 of .50moa.

Ek dink daar is n ander rede vir wat jy ervaar het. Soos die dag warmer raak en jou ammunisie warmer word en as jy dalk met n skoon loop begin het die oggend, is dit meer waarskynlik dat jou spoed toegeneem het en jy nou hoër skiet eerder as die suiwer effek van sonlig.

Kan ek voorstel dat jy die artikel se gevolgtrekkings heroorweeg.

Dag Frikkie
Ek dink nie jy lees mooi nie. Gaan lees die artikel weer. Jy verstaan ook nie Gregor Woods se verduideliking reg nie. My artikel sê presies dieselfde as wat jy sê. As jy bult op of bult af skiet sal die koeël beinvloed word deur die horisontale afstand en nie die gemete afstand teen die bult op of af nie. Ek het ook aan die einde 'n tabel ingesluit wat aandui hoeveel jy moet laer mik of liewer vir watter afstand jy moet kompenseer as jy berg-af of berg-op skiet.

Wat ek sê is dat helling (die hoek waarteen jy skiet) nie so 'n groot invloed het op normale jagafstande nie (dis nou waar jou gewone jagter skiet tot op afstande van ongeveer 300m). Ek sê ook dat die helling nie so 'n groot invloed het nie want ons dink ons skiet teen 'n baie steil helling en dan is dit die meeste kere ver onder 20 grade. Dus as die bok skuins teen die helling onderkant jou staan op 260m gemeet, kan jy maar jou 260m-stelling gebruik, jy sal die bok nie misskiet nie... jy gaan net effens hoog skiet. My praktiese toets op die rooibokteiken bewys dit. In plaas daarvan dat die gewone man hom moet bekommer oor hoeveel hy moet laer mik en of hy moet laer mik op 260m, kan hy net eenvoudig sy normale 260m stelling gebruik of dan effens hoër mik as sy geweer op 200m ingestel is. Onthou, die helling is die kwessie, ek sê weer ons skiet glad nie teen sulke steil hellings as wat ons dink nie en die hellings waarteen ons skiet is te min om enige noemenswaardige invloed te hê.

Die fout wat baie mense maak is om nie mooi te lees nie of nie 'n artikel in sy volledigheid te lees en te verstaan nie. Dus, gaan lees weer mooi... ek stem saam met jou. Moet ek dit in Afrikaans vertaal?

[Koos Barnard]

Frikkie, jy is reg Gregor se stelling is verkeerd en moes gekwalifiseer gewees het om dit te verstaan. Ek verstaan ook waar die verwarring inkom aan die einde van die artikel waar ek sê dat jy hoër moet mik. Die volgende sin kwalifiseer egter hoekom ek dit sê maar ek besef dat mense dit verkeerd kan verstaan. Dit moet nog beter gekwalifiseer wees. In plaas daarvan om te gesê het, "Mik hoër..." moes ek eers geskryf het dat jy altyd hoër sal tref of jy bult-op of bult-af skiet maar dat ons normaalweg teen sulke klein hellings skiet dat ons nie hoef te kompenseer nie en net op die afstand hoef te werk wat ons range. Sodra die helling se gradiënt groot raak moet jy laer mik of dan vir korter afstande kompenseer soos in die tabel uiteengesit. Ek hoop dit verduidelik die ding beter. Ek sal vra of Magnum bereid sal wees dat ons 'n kort en beter verduideliking plaas. Mooi loop

[Frikkie Coetzee]

My genade Koos.

Eers se jy my sleg. Dan se jy ek is reg. Jy se ek kan nie Engels lees nie maar jy erken artikel is verwarend en moes beter verduidelik word.

Moenie worry nie. Ek kan Engels verstaan. En ek het jou artikel n paar keer gelees voor ek geantwoord het.

Maar jy weet wat die ou gesegde se: n Halwe begrip benodig n goeie verduideliking.

[Koos Barnard]

Frikkie
Jammer maat, as ek jou beledig het, vra ek om verskoning.
Mooi loop

[Ratel]

Dankie vir die deel Koos. Het hierdie vanoggend raak gelees.
https://www.gameandfishmag.com/editoria ... les/542356
Dit se dieselfde as wat jy in jou pos gedeel het.

[Koos Barnard]

Ratel baie dankie, dis presies wat ek probeer sê het. Baie mense verstaan dit reg (ek het verskeie oproepe/whatsapps ontvang) maar daar is sommiges wat nie doen nie. Ek sal later weer n update post met vereenvoudigde verduideliking want soos die artikel nou staan is dit blykbaar verwarrend vir 'n paar mense.
Mooi loop