demonwolf444 Posted November 21, 2011 Report Share Posted November 21, 2011 i remember reading on here someone saying about hold over changing when shooting up and shooting down, cannot get my head around it and couldnt find the Op, could someone please link me, or clarify Quote Link to comment Share on other sites More sharing options...
Farmer-of-the-Futre Posted November 21, 2011 Report Share Posted November 21, 2011 I think i saw the thread too. Im pretty sure you have to aim lower when shooting higher and vise versa Quote Link to comment Share on other sites More sharing options...
Vipa Posted November 21, 2011 Report Share Posted November 21, 2011 (edited) Hold under for uphill OR downhill shooting... it's a trig problem and is very straightforward (if you have a calculator or tables handy)... the cosine of the angle of the shot will give you the fraction if the straight line distance... sooooo... let's say you are shooting a deer, uphill... (obviously not with an air rifle!) You range the deer and it's 100 yds, you measure the angle on an inclinometer and you get 30degrees... the calculation is thus Cos 30 = 0.866 therefore the 'shoot's like' didtance will be 86.6yds This little pic may help.. Edited November 21, 2011 by Vipa Quote Link to comment Share on other sites More sharing options...
FalconFN Posted November 21, 2011 Report Share Posted November 21, 2011 That's not the only reason. The line of your scope and barrel are set to converge so when you fire a pellet at a target that is horizontal to you and at a normal air gun range, your barrel will in fact be slightly inclined to compensate for the gravitational pull on the pellet. The pellet will travel in an arc (parabola) and will be dropping when it reaches the target (the pellet intersects the line of your scope twice on it's journey, that's why you have two zero points). If you are shooting vertically up, gravity will not effect the trajectory of the pellet, only the height it will reach so the pellet will appear to meet the first zero point and then contine to travel above your crosshairs without dropping back for your second zero point. At 45 degrees the pellet will have an arcing trajectory but it will not be as pronunced so again the pellet will strike high. Quote Link to comment Share on other sites More sharing options...
Dekers Posted November 21, 2011 Report Share Posted November 21, 2011 Hold under for uphill OR downhill shooting... it's a trig problem and is very straightforward (if you have a calculator or tables handy)... the cosine of the angle of the shot will give you the fraction if the straight line distance... sooooo... let's say you are shooting a deer, uphill... (obviously not with an air rifle!) You range the deer and it's 100 yds, you measure the angle on an inclinometer and you get 30degrees... the calculation is thus Cos 30 = 0.866 therefore the 'shoot's like' didtance will be 86.6yds This little pic may help.. Good guide, not seen that illustration before, people do tend to struggle with this up/down hill business for some reason! Just the same, I have my reservations about shooting a sheep with an air rifle up hill at 100 yards..... Quote Link to comment Share on other sites More sharing options...
Vipa Posted November 21, 2011 Report Share Posted November 21, 2011 Good guide, not seen that illustration before, people do tend to struggle with this up/down hill business for some reason! Just the same, I have my reservations about shooting a sheep with an air rifle up hill at 100 yards..... Nahhhh... just think of it like an HMR.............. only better Quote Link to comment Share on other sites More sharing options...
kent Posted November 22, 2011 Report Share Posted November 22, 2011 Were you hold depends on your range in relation to your trajectory, it sounds way more complecated than it is actually. Just take the horizontal (level) range for trajectory and hold over or under acordingly if shooting either up or down it makes no matter then use the distance the pellet travels for wind. For example 1. if shooting directly upwards ( totally vertical) you would allow no trajectory arc so would aim high the same as if shooting at on object directly at the end of your muzzle. However you would have to allow windages as per the distance the pellet was to travel. I hope this dispells any "always hold under" rubbish Quote Link to comment Share on other sites More sharing options...
timmytree Posted November 22, 2011 Report Share Posted November 22, 2011 Were you hold depends on your range in relation to your trajectory, it sounds way more complecated than it is actually. Just take the horizontal (level) range for trajectory and hold over or under acordingly if shooting either up or down it makes no matter then use the distance the pellet travels for wind. For example 1. if shooting directly upwards ( totally vertical) you would allow no trajectory arc so would aim high the same as if shooting at on object directly at the end of your muzzle. However you would have to allow windages as per the distance the pellet was to travel. I hope this dispells any "always hold under" rubbish Surely if your barrel is true vertical then a pellet will cross the line of sight only once, up to that point a pellet is showing low so you would aim high. After the pellet has crossed the line of sight it would show high on the crosshair so you would need to aim low? Quote Link to comment Share on other sites More sharing options...
kent Posted November 22, 2011 Report Share Posted November 22, 2011 Surely if your barrel is true vertical then a pellet will cross the line of sight only once, up to that point a pellet is showing low so you would aim high. After the pellet has crossed the line of sight it would show high on the crosshair so you would need to aim low? Ok granted its just an over simplication for explaination purpose only- i have yet to see anyone actually take such a shot and have never taken one myself, besides anything else that pellet is gonna hurt some when it comes back down if you did . Its my mistake though for not thinking through my explaination example in relation to std airgun tragectories as my mind is more locked into 3000 fps and 130yds zeros these days. The point is that although your fairly usual airgun 8 yds zero will still stand your 30 or 35yd zero will depend on the horizontal range so you don't always hold low. my mind just jumped ahead too far ahead in my example Quote Link to comment Share on other sites More sharing options...
Vipa Posted November 22, 2011 Report Share Posted November 22, 2011 (edited) Ok granted its just an over simplication for explaination purpose only- i have yet to see anyone actually take such a shot and have never taken one myself, besides anything else that pellet is gonna hurt some when it comes back down if you did . Its my mistake though for not thinking through my explaination example in relation to std airgun tragectories as my mind is more locked into 3000 fps and 130yds zeros these days. The point is that although your fairly usual airgun 8 yds zero will still stand your 30 or 35yd zero will depend on the horizontal range so you don't always hold low. my mind just jumped ahead too far ahead in my example I think you've just made it Way more complicated! 'just take your level or horizontal range' ok.. so you know that your target is at a 45 degree upward angle and is 30 yards away... please explain how you would get your 'level' range for that. Also... uphill or downhill.. the projectile will ALWAYS impact higher than your crosshairs would have you believe if you range it and then shoot for that range, therefore you would ALWAYS either dial in a shorter (shoots like) distance and use the crosshairs OR don't touch the turrets and hold slightly under... there would NEVER be an occasion to hold over in the circumstance being discussed... You are bringing another issue into the equasion... that of range.. i.e. if you are shooting a target at 45 degrees up and it is 50 yards away but you are zeroed at 10 yards then, yes, there would be hold over because of the distance, it still wouldn't be as much holdover as it would if you were shooting level... Therefore for the sake of accuracy, always do the math and obtain a 'shoots like' distance then just carry on as normal as Kent suggests... At the end of the day, as I have already said, shooting uphill or downhill, the projectile will ALWAYS strike higher than it would on a target at the same actual distance if shooting horizontally so just be aware of it and compensate for it by aiming 'relatively' lower.. Edited November 22, 2011 by Vipa Quote Link to comment Share on other sites More sharing options...
demonwolf444 Posted November 22, 2011 Author Report Share Posted November 22, 2011 Really usefull stuff thankyou guys I think I have it figured now, it would also explain why two pigeons were laughing at me yesterday! Part of the problem is I often shoot targets in my garden wheb I cannot get onto my permission, which is a steep slope downwards, so when I sight in in the garden the zero is different to when I sight it in in the fields. And so it is obvious I will have to adjust where my targets are...thankyou allot guys very informative and a credit to the forums! Quote Link to comment Share on other sites More sharing options...
Vipa Posted November 22, 2011 Report Share Posted November 22, 2011 (edited) Really usefull stuff thankyou guys I think I have it figured now, it would also explain why two pigeons were laughing at me yesterday! Part of the problem is I often shoot targets in my garden wheb I cannot get onto my permission, which is a steep slope downwards, so when I sight in in the garden the zero is different to when I sight it in in the fields. And so it is obvious I will have to adjust where my targets are...thankyou allot guys very informative and a credit to the forums! You will make life much easier for yourself if you zero flat. you won't notice much difference at sensible ranges upto about 15 degrees when out shooting and therefore won't even need to think about angle 99% of the time... if you are zeroed at a steep angle then you will need to think about angles all of the time.. Edited November 22, 2011 by Vipa Quote Link to comment Share on other sites More sharing options...
demonwolf444 Posted November 23, 2011 Author Report Share Posted November 23, 2011 its not a massive angle just enough to make a difference! but yes i need to re-zero Quote Link to comment Share on other sites More sharing options...
kent Posted November 25, 2011 Report Share Posted November 25, 2011 'just take your level or horizontal range' ok.. so you know that your target is at a 45 degree upward angle and is 30 yards away... please explain how you would get your 'level' range for that. look at it and estimate, based on field shooting not ft this in reality is the only way you can do it on quarry. Shooting up into a tree? then look at the tree base call a range then knock off or add on depening if the quarry is forwards or back of that in the branches (this is your range for trajectory), wind is like i say the distance the pellet actually travels Quote Link to comment Share on other sites More sharing options...
Dougy Posted November 25, 2011 Report Share Posted November 25, 2011 you wont go far wrong spending a few hours practicing in the wood were you have permission. pick branches or leaves at different hights ,angles and making a mental.note were you actually need to aim to hit the point. Time practicing will be rewarding jn the long run. Of course all shots will be safe. Quote Link to comment Share on other sites More sharing options...
demonwolf444 Posted November 25, 2011 Author Report Share Posted November 25, 2011 In all honesty i'd never really taken it in to account. I guess most my up hill shots must have been at a close enough range for it not to make any difference! just was taking a shot on a pigeon that was vertically directly above me but a fair way up and it didnt even seem to realise!, remembered reading a post on here and thought i'd ask! very helpfull though! i want to get a lazer range finder and so i can say with absoloute precision how far away my target was as ive .only ever paced out shots before and even that isnt very accurate! ha Quote Link to comment Share on other sites More sharing options...
brian45 Posted November 27, 2011 Report Share Posted November 27, 2011 any of you guys with an iphone can download chairgun from the app store, very handy tool will show how much hold over/under Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.