Zero scope for steep angles  

 

rocker
(@rocker)
Joined:2 months  ago
Posts: 5
June 12, 2018 23:04  

Hello, all! Im new here, this is my first post. I just wanted to say I've been looking for some help on an issue, of how to zero my Snow Wolf scope for shooting at steep angles. I use my rifle exclusively for pest control, mainly pigeons which have invaded my housing development over the last few years. As a result, I am often shooting upwards at the pests, standing on my window ledges, at angles of 60 - 75 degrees. This sentence, in an old post, helped more than all the research I've done to date. 

 "  airgun, archery or powderburner...aim lower when shooting at up OR downhill... 

      only experience will show you how much."

So simple when someone with experience encapsulates it so succinctly.

This looks like a great site, I look forward to many more chats and questions.

 

Thanks! 


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JW652
(@jw652)
Joined:7 months  ago
Posts: 24
June 13, 2018 09:40  

The quote is exactly correct. There are other solutions like using the vertical measurement to the target or an inclinometer, but they require a measuring device and extra time, both of which are often not available for a snap shot.

Live on a farm and exercise the same kind of pest control several times a week. For ranges out to 30 or so yards on birds, have found that low power and a flathead (match) pellet works best for me and prevents over penetration and damage to metal roofs on barns.

Welcome to the Forum, and have fun!


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therealld
(@therealld)
Joined:7 months  ago
Posts: 16
June 13, 2018 11:58  

I'll add that very low open sights are about the best for close, high angle shots, or at least, the use of the lowest mounts for the scope.

The relationship of scope line of sight to boreline has a greater impact for short range shots than most changes in aiming angles.


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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined:7 months  ago
Posts: 71
June 13, 2018 17:17  

If you get an inclinometer, like this one:

https://www.ctcustomairguns.com/the-x-10-tiltmeter.html  

And a ballistic calculator, like this one:

https://www.ctcustomairguns.com/pellet-path-calculator.html  

It will all boil down to measuring the angle, entering it in the app, and letting the app tell you where your pellet is flying at the distance and the angle.

You may read somewhere, to follow the "cosine rule" or to measure the horizontal distance and use that. It is not completely true for airguns because of the many shots we take SHORTER than our first zero.

If you load the app in an Android device that already has a camera and an inclinometer (most smartphones), the app will be able to pickup the inclination to the target and correct the complete trajectory.

It will be up to you to estimate the LOS distance and the wind conditions at higher elevations.

HTH

 

 

HM


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Feinwerk
(@feinwerk)
Joined:7 months  ago
Posts: 7
June 14, 2018 14:10  

If you are using a Mil Dot scope you have to learn how to hold *under* at various angles and choose the appropriate mil dot *above* your the crosshairs Center Point to put the point of impact where you want it.

I sight in my guns as normal on a horizontal plane and then learn the correct hold under for shooting up or down at angles. It will surprise you how far under you have to hold at high angles. The best way I have found to do this is to shoot at sample targets at actual distances or place them where pests usually Roost and take practice shots to learn exactly which hold over dot/point is best.

Another way to do this is to take practice shots at a spot of bark on a tree and note where the pellet hits in relation to your point of aim and then you can adjust the hold for that angle.


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Doug Wall
(@doug-wall)
Joined:7 months  ago
Posts: 51
June 14, 2018 17:08  

Please take note that this guy is shooting AIRSOFT, with plastic BBs at very close ranges. I wouldn't be using a real airgun to shoot anything off window ledges.


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Pistoleer
(@pistoleer)
Joined:7 months  ago
Posts: 39
June 16, 2018 11:55  

As mentioned, Airguns aren't the same as pb's, but this a great tool to start your estimation while hunting... Some times you don't have time to whip out your phone, this is a quick guide-

Angle/Degree to Cosine Multiplier
Degree of angle           Multiplier of Measured Yards
5                                  .99 or 99%
10                                 .98 or 98%
15                                 .96 or 96%
20                                 .94 or 94%
25                                 .91 or 91%
30                                 .87 or 87%
35                                 .82 or 82%
40                                 .77 or 77%
45                                 .70 or 70%
50                                 .64 or 64%
55                                 .57 or 57%
60                                 .50 or 50%
65                                 .42 or 42%
70                                 .34 or 34%
75                                 .26 or 26%
80                                 .17 or 17%
85                                 .09 or 9%
90                                 .00 or 0%

Read more:  http://www.rifleshootermag.com/network-topics/tips-tactics-network/hi


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Steve in NC
(@steve-in-nc)
Dealer
Joined:7 months  ago
Posts: 221
June 16, 2018 20:26  
Posted by: Pistoleer

As mentioned, Airguns aren't the same as pb's, but this a great tool to start your estimation while hunting... Some times you don't have time to whip out your phone, this is a quick guide-

Angle/Degree to Cosine Multiplier
Degree of angle           Multiplier of Measured Yards
5                                  .99 or 99%
10                                 .98 or 98%
15                                 .96 or 96%
20                                 .94 or 94%
25                                 .91 or 91%
30                                 .87 or 87%
35                                 .82 or 82%
40                                 .77 or 77%
45                                 .70 or 70%
50                                 .64 or 64%
55                                 .57 or 57%
60                                 .50 or 50%
65                                 .42 or 42%
70                                 .34 or 34%
75                                 .26 or 26%
80                                 .17 or 17%
85                                 .09 or 9%
90                                 .00 or 0%

Read more:  http://www.rifleshootermag.com/network-topics/tips-tactics-network/hi

Sanity check:  Suppose the gun/sight combo has near/far zeroes at 10 and 25 yards, the distance to the target is 10 yards, and the angle of the shot is 45 degrees.  According to your table, a shot taken at 45 degrees should be ranged for 70% of the actual range to the target. 

That is to say, in this case, for 7 yards.  

Question:  How can the following two conflicting ballistic truisms be reconciled?

1. Shots taken inside the near zero always require hold over.

2. Shots taken at high angles of elevation (or depression) always require hold under.

The cosine rule is therefore telling us to hold both over and under at the same time.

How is that done?

temp


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Doug Wall
(@doug-wall)
Joined:7 months  ago
Posts: 51
June 16, 2018 20:48  

To get back to the OP's original question about adjusting his airsoft rifle for shooting at high angles. Since his airsoft rifle has a Hop-up, which imparts backspin to the plastic BB, there is very little that our usual formulas and estimates can do for him. BB's with back spin can actually curve upwards and climb after being shot


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Steve in NC
(@steve-in-nc)
Dealer
Joined:7 months  ago
Posts: 221
June 16, 2018 21:46  
Posted by: Doug Wall

To get back to the OP's original question about adjusting his airsoft rifle for shooting at high angles. Since his airsoft rifle has a Hop-up, which imparts backspin to the plastic BB, there is very little that our usual formulas and estimates can do for him. BB's with back spin can actually curve upwards and climb after being shot

Interesting point, but since the effect of gravity changes with inclination even for a trajectory affected by Magnus-effect lift, the OP will need to hold under for inclined shots just like we do.


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