Less than 15% angle shots.

Scratchthejeepguy

Sergeant
Full Member
Minuteman
Mar 27, 2013
214
0
WI
I've been told that any angle shots, up or down, less than 15% should be considered flat, as far as POA/POI goes. And according to my MIL dot master, there's no calculations for anything under 15% which would support this theory.

I guess I didn't realize just how much of an angle 15% actually is. I was scouting a new location today for a 100-400 yard shooting lane, and as I went farther away, I had to go up a large hill. When I got to the top of the hill and I could see the target, I checked the angle it was about 13-14 degrees downhill from the firing position to the target.

I know it's only 13-14 degrees, but it sure seems like a steep angle. Will this have any effect on POI.

FYI, I'm shooting .308.
 

timelinex

Gunny Sergeant
Full Member
Minuteman
  • May 7, 2011
    1,379
    29
    Scottsdale,Az
    I've been told that any angle shots, up or down, less than 15% should be considered flat, as far as POA/POI goes. And according to my MIL dot master, there's no calculations for anything under 15% which would support this theory.

    I guess I didn't realize just how much of an angle 15% actually is. I was scouting a new location today for a 100-400 yard shooting lane, and as I went farther away, I had to go up a large hill. When I got to the top of the hill and I could see the target, I checked the angle it was about 13-14 degrees downhill from the firing position to the target.

    I know it's only 13-14 degrees, but it sure seems like a steep angle. Will this have any effect on POI.

    FYI, I'm shooting .308.

    Honestly, just use a ballistics calculator and you will know exactly the difference for your round.

    Even small angles in the single digits, will make a reasonable difference as you increase distance.....

    It might make no realistic difference at 100 yards, but at 1000 or even a mile, it starts making all the difference.

    Edit: as an example, in my 308 at 1000 yards, a 10 degree look angle will change elevation by about half a foot. Biggest deal? No. But it could mean the difference between a first round hit or miss
     
    Last edited:

    KTDLS7

    Sergeant
    Full Member
    Minuteman
    Apr 11, 2010
    621
    2
    D-FW, TX
    I've been told that any angle shots, up or down, less than 15% should be considered flat, as far as POA/POI goes. And according to my MIL dot master, there's no calculations for anything under 15% which would support this theory.

    I guess I didn't realize just how much of an angle 15% actually is. I was scouting a new location today for a 100-400 yard shooting lane, and as I went farther away, I had to go up a large hill. When I got to the top of the hill and I could see the target, I checked the angle it was about 13-14 degrees downhill from the firing position to the target.

    I know it's only 13-14 degrees, but it sure seems like a steep angle. Will this have any effect on POI.

    FYI, I'm shooting .308.

    I may be mis-reading your post, but it appears you are mixing % slope (grade) and angle in degrees (*).

    15% slope (or grade) = 8.53* (angle)
    15* (angle) = 26.79% Slope (or grade)

    (If my calculations are correct)
    Using your max range of 400 yds:
    o 15% slope (grade) corrects to 396 yds
    o 15* angle corrects to 386 yds

    . . . or use your shooter calculator . . .
     

    KYpatriot

    Sergeant
    Full Member
    Minuteman
    Mar 31, 2009
    702
    65
    48
    wishing i was in KY
    Typically for shooting purpose we should always talk in degrees, so we can use the cosine formula. There is nothing wrong with measuring the shot angle and accounting for it. If you are using none of the popular ballistic apps on a smartphone there is a pretty cool theodolite app test will give you the angle and bearing to anything under the crosshairs as well as a plumb and horizon reference.

    The fact is though for small angles the effect is very minor. A ten degree angle will look like a significant elevation change at a thousand yards, but even so won't effect the solution as much as the range ambiguity you will get at that range from most of the popular rangefinders. But, it is there and if you account for it you should be closer all other things equal.
     

    KTDLS7

    Sergeant
    Full Member
    Minuteman
    Apr 11, 2010
    621
    2
    D-FW, TX
    Typically for shooting purpose we should always talk in degrees, so we can use the cosine formula. There is nothing wrong with measuring the shot angle and accounting for it. If you are using none of the popular ballistic apps on a smartphone there is a pretty cool theodolite app test will give you the angle and bearing to anything under the crosshairs as well as a plumb and horizon reference.

    The fact is though for small angles the effect is very minor. A ten degree angle will look like a significant elevation change at a thousand yards, but even so won't effect the solution as much as the range ambiguity you will get at that range from most of the popular rangefinders. But, it is there and if you account for it you should be closer all other things equal.

    ^ ^ ^ Could not agree more! ^ ^ ^ and don't overthink it. Using the example above (1000 yd & 10* angle), the corrected distance is 985 yds - a 1.5% error.

    % Slope (or Grade) is for roadways, not shooting solutions - use angle in degrees to target.

    I still have, and use tables, in event of an electronic failure :)