Determining shot angle (Inclination)

[MagnumManiac]

Quite simple, ANY up/down angle means a flatter trajectory than what your standard range finder says, so you aim SLIGHTLY low with either circumstance.

350yrds is not a lot, so maybe an inch or so low is all that's needed.

Cheers.

 

[Mram10us]

Depends on cartridge, but a 308 with 172 mil ammo, at 350 yards with a 200 yard zero is:
Level ground -17.5"
20deg - 15.2"

 

[BrentM]

200-350 is pretty short distance to worry about slope unless it's a super slow bullet or super steep slope. I'd suggest just using your phone for now to get the slope angle and pretty soon you'll have a solid feel for it and will know what to use. If you use a ballistic app then your issue is solved as you have the ability to run the slope from the phone and it uses that data to adjust your dial.

Also, as a tip. Don't adjust your distance, adjust your dial. For example if you are shooting 1000 yards and the slope angle math says shoot to is 950, it is wrong. You want to use the dial up and adjust it. So if the dial is 20 moa for 1000, 18 for 950, you actually will want to take 5% of the 20 moa dial which is 19 moa.

 

[Mram10us]

200-350 is pretty short distance to worry about slope unless it's a super slow bullet or super steep slope. I'd suggest just using your phone for now to get the slope angle and pretty soon you'll have a solid feel for it and will know what to use. If you use a ballistic app then your issue is solved as you have the ability to run the slope from the phone and it uses that data to adjust your dial.

Also, as a tip. Don't adjust your distance, adjust your dial. For example if you are shooting 1000 yards and the slope angle math says shoot to is 950, it is wrong. You want to use the dial up and adjust it. So if the dial is 20 moa for 1000, 18 for 950, you actually will want to take 5% of the 20 moa dial which is 19 moa.

Never heard that last part. Interesting

 

[BrentM]

Never heard that last part. Interesting

That is how a ballistic computer does it. Regardless of the slope your bullet still travels the true distance. The riflesmans rule says to take the slope angle calculation from the distance. It is close enough for sub 500 and shallower slope but once the distance or slope increases the data is inaccurate.

The proper method is based on TOF. To do this in simple fashion vs the mathematic equation you adjust the dial. To test this, use your app and run a test for a 20 degree slope at 1000. Let the app show you the dial. Now, 0 out the slope and adjust the distance to the slope angle which is .94% or 940 yards. It should be pretty apparent there is significant difference in what the app tells you vs the shoot to distance based on the slope/cosine angle.

 

[dfanonymous]

That is how a ballistic computer does it. Regardless of the slope your bullet still travels the true distance. The riflesmans rule says to take the slope angle calculation from the distance. It is close enough for sub 500 and shallower slope but once the distance or slope increases the data is inaccurate.

The proper method is based on TOF. To do this in simple fashion vs the mathematic equation you adjust the dial. To test this, use your app and run a test for a 20 degree slope at 1000. Let the app show you the dial. Now, 0 out the slope and adjust the distance to the slope angle which is .94% or 940 yards. It should be pretty apparent there is significant difference in what the app tells you vs the shoot to distance based on the slope/cosine angle.

You're not wrong. There's other things at work, depending on the app we are talking about, it's also calculating voodoo that is the DA above lines of sight in max ord. This is why in software it's important to differentiate negative or positive shooting scope angle with software.

 

[BrentM]

You're not wrong. There's other things at work, depending on the app we are talking about, it's also calculating voodoo that is the DA above lines of sight in max ord. This is why in software it's important to differentiate negative or positive shooting scope angle with software.

Of course it takes into account DA, but the end result is still the same. Cosine math is not accurate for distance, it is accurate for TOF. TOF is affected by external ballistics.

Simplest way to calculate the change for slope is to determine your dial to solution, then multiply that my the correction factor.

5 = .99
10 = .98
15 = .96
20 = .94
25 = .90
30 = .87

 

[emp1953]

For a long shot you need the distance. An inclinometer works fine and gives you an angle probably within a couple degrees, depending on the user and their skills and method. Just invest in a range finder. Most give you the angle along with the critical range. If taking the angle of elevation into account is critical you will need a rather capable ballistics calculator along with you as well. Or a well planned out ballistics chart, with trajectories at known angles, integral calculus will provide you with results that will account for the changing effects of gravity with changing angles of elevation. There too you require the range. If shooting long distances, an accurate range is critical since bullet drop at the end of a long distance shot is measured in feet and is accentuated for each additional yard of distance.

 

[Hawryluk]

Take the cosine of the angle you're shooting multiply that by the distance then adjust your scope for the new shooting distance orrrrr just get an angle compensating range finder. Good luck!

 

[DavidleeCole]

At the height of your stand and the distance of the 250 to 300 yard shot there is only around a yard more distance in the shot. You can get a range finder as stated before but you have to remember true distance and actual distance will be different and gravity and wind will be different so you have to keep them straight in your head to properly adjust your shot. It makes alot more difference for us in the south if we are bow hunters and for the folks out west that hunt in the mountains.

 

[BrentM]

35ft up a stand, 200-350 yards is nothing. The slope to distance change is very minor and not worth this overall discussion.

Likely what is happening is your alignment to rifle has changed and shifting your point of impact since your sight alignment is slightly off. Things don't really start changing until you hitting long range or slopes in the 15-20 degree range.

 

[George Dean]

Depends on cartridge, but a 308 with 172 mil ammo, at 350 yards with a 200 yard zero is:
Level ground -17.5"
20deg - 15.2"

Isn't M80 NATO ball 147 gr? Not quibbling but I have tons of 147. I also shoot Federal Gold SMKs in 168 & 175. I am unfamiliar with a 172. The 168s my favorite.

Apologies for drifting off topic.

 

[Mram10us]

Isn't M80 NATO ball 147 gr? Not quibbling but I have tons of 147. I also shoot Federal Gold SMKs in 168 & 175. I am unfamiliar with a 172. The 168s my favorite.

Apologies for drifting off topic.

M118 172 stuff I have. I'll verify when I get time. Guessing the 168 and 175s would be about the same at that range

 

[George Dean]

M118 172 stuff I have. I'll verify when I get time. Guessing the 168 and 175s would be about the same at that range

;-) No need, Google's my friend also. Thank you.