As a Floridian, figuring come-ups when shooting uphill/downhill is something I've never had to deal with. Nevertheless, I find the subject interesting. I recently came across an article that had a simple table that would allow some quick mental math to figure come-ups when shooting at an angle.
Basically, you estimate the distance to the target, and the angle. Find the angle in the table, then multiply your estimated distance by the percentage in the table to determine your come-up. This would be a rough approximation, and really isn't significant until you start dealing with extreme angles and long distances.
5-10 degree slope = 98% of slope distance
15-20 degree slope = 95% of slope distance
25-30 degree slope = 90% of slope distance
35-40 degree slope = 80% of slope distance
45 degree slope = 70% of slope distance
Thought some of you might find this interesting as well.
Here is the article: https://gundigest.com/how-to/training/trajectory-angle-shooting-rifles
That's cool Angel. Thanks for sharing.
Nice work. :snipersmi
Quote from: Savage22 on April 08, 2018, 04:42:32 PM
As a Floridian, figuring come-ups when shooting uphill/downhill is something I've never had to deal with. Nevertheless, I find the subject interesting. I recently came across an article that had a simple table that would allow some quick mental math to figure come-ups when shooting at an angle.
Basically, you estimate the distance to the target, and the angle. Find the angle in the table, then multiply your estimated distance by the percentage in the table to determine your come-up. This would be a rough approximation, and really isn't significant until you start dealing with extreme angles and long distances.
5-10 degree slope = 98% of slope distance
15-20 degree slope = 95% of slope distance
25-30 degree slope = 90% of slope distance
35-40 degree slope = 80% of slope distance
45 degree slope = 70% of slope distance
Thought some of you might find this interesting as well.
Here is the article: https://gundigest.com/how-to/training/trajectory-angle-shooting-rifles
Interesting read.
Some simple ballpark numbers like above make sense and put it into perspective.
At the Rifleman's Quarter Mile (500 yards) you need a 30 degree slope to create a 50 yard difference between actual and compensated distance which would be about a 2 MOA change.
If it was a 15 degree slope at 300 yards the adjustment is to 285 yards so we're only talking about a .2'ish MOA change in POI so not even worth worrying about.
Set your smart phone on it's angle finder/inclinometer and see how severe 30 degrees is to see if you even need to worry about it.
It's a fun mental exercise and I'll use it if I'm ever doing mountainous long range hunting. The reality is for Appleseed's purposes sweating out angles is like worrying about the rounding errors in an actual MOA vs. a Shooter's MOA.
Thanks for posting it!
Realistically, unless you are shooting up/down a mountain, its not significant or worth worrying about within a Rifleman's quarter mile.
My previous understanding was simply "aim low", but how low is low? At what point do I start aiming low? This helps quantify it.
Glad to see some folks enjoying that article.
Quote from: Savage22 on April 10, 2018, 09:27:12 PM
My previous understanding was simply "aim low", but how low is low? At what point do I start aiming low? This helps quantify it.
Definitely not just "aim low" but I guess in the sense of the effective distance to target being less it is "don't dial/hold as much".
Quote from: Savage22 on April 10, 2018, 09:27:12 PM
Realistically, unless you are shooting up/down a mountain, its not significant or worth worrying about within a Rifleman's quarter mile.
It depends. A good rule of thumb is to make the correction iff (if and only if) you are shooting at 200 yards or more AND up or down slopes of 20 degrees or more. Or, whenever shooting at smaller targets.
It was the difference at the Battle of Kings Mountain, between flat lander militia riflemen from the low country militia vs. the over mountain men militia from the high country. Both sides were taking headshots. The death tolls were 290 flatlanders vs. 29 over mountain men. The flatlanders approach had their bullets going about 6-9 inches above the aim points, or just over the heads of the over mountain men.
The result was a 10-fold difference in effectiveness. Between roughly the same numbers of men on both sides, numbering about 1,500 each. With both trained to roughly the same proficiency on flat land.
Patrick Ferguson was one of the casualties. He was the sole British officer present.
I walked the battlefield a couple years ago. A Very Somber Walk in the Woods. The battle was a major turning point in the southern plan of the British attempt to go northward, to retake the colonies in rebellion, after the loss at Saratoga.
Don't be a low lander. Be an Over Mountain Man. Know when it matters to correct for slope.
Or, as Colonels Crockett, Sevier, and Shelby told their Over Mountain Men, "Boys, Remember, Shoot a Little Low!"
Sevier became the first governor of Tennessee. Shelby became the first governor of Kentucky. And, Crockett had a son named Davey who would figure prominently at the Alamo. But, that is a story, for another day.
â€"gb
QuoteIt was the difference at the Battle of Kings Mountain, between flat lander militia riflemen from the low country militia vs. the over mountain men militia from the high country. Both sides were taking headshots. The death tolls were 290 flatlanders vs. 29 over mountain men. The flatlanders approach had their bullets going about 6-9 inches above the aim points, or just over the heads of the over mountain men.
I had never heard of the Battle of Kings Mountain. I'll have to do some reading, sounds like a very interesting story. Thanks for sharing.
the battle of kings mountain was 1780 so we are talking patched round ball where you would need approximately 4 to 5 feet of elevation correction for the Morgan shingle at 250 yards depending on your sight in distance.
a ball is falling very fast at those distances and 10 yards can make a several inch difference when your 45caliber ball is 144gr with a BC of 0.064 and even figuring about 2000fps
the difference between 225 yards and 250 yards is about 16 inches so an 8-10 inch miss at that range would be close to expected on a 10 yard miscalculation in distance .
but if we are talking a modern 223 or 308 we are talking a 1-2 inch difference between 225 yards and 250 yards and an inch or less on a 10 yard miss calculation
After I cover angle shooting during a KDC class, I offer the simple method - when shooting uphill or downhill, aim a bit low. The angle has to be fairly extreme for a serious correction from what I am told by thems who have actually done it. Like S22 stated, here in what was once the very flat sea floor, we don't get much practice. ^-^
the discussion for AS purposes at a AS or KD is like you said best left brief , because it could be it's own weekend course if you could find a range where you could get the distance and elevation.
It really ends up falling under advanced independent study.
one thing to offer is there are very good calculators out there for free Hornady's ballistic calculator will let you enter your load and change slope angles but unconfirmed data is just that.
first knowing your velocity , BC , optic height above bore axis and sight in distance entering that and taking that data to the range to confirm it matches very close to the calculated data.
then building a chart of distance to slope angel and adjustment using the calculator then going out and confirming that at any angle you can get
if your willing to trade some money for a time savings I use an app Strelok Pro at a cost of 12 dollars for the android version download it is a very convenient portable tool when installed on a smart phone. there is a free version but I am not sure it includes slop angle calculation.
still unconfirmed data until you test some of it to verify.
if you think of a 30 60 90 right triangle this would diagram the height and distance with the hypotenuse being the bullets approximate path running the numbers on a target 400 yards out at a 30 degree slope using a fairly common 308 load it would require about 5 inches less elevation correction than a shot on flat ground. but you would also be 692 feet above the target if you figure that at roughly 16 feet per floor in a commercial building you would be looking at 43 floors up equivalent.
Quote from: Lomshek on April 10, 2018, 03:51:21 PM
It's a fun mental exercise and I'll use it if I'm ever doing mountainous long range hunting. The reality is for Appleseed's purposes sweating out angles is like worrying about the rounding errors in an actual MOA vs. a Shooter's MOA.
Very true.
But I'm surprised nobody mentioned "cosines" (for those folks academically inclined). If you multiply the cosine of the angle by the range as you see it, the result will be the range to target to be used (range under the direct influence of gravity). As an example, the cosine of a 45 degree angle is approx 0.707. If your observed range to target was 373 yds, the "real" range would be approx 264 yds (0.707 X 373 yds).
Regardless aiming up or down your aim will always be at 6 o'clock (unless you compute and apply a correction to the sights).
aj
some of my geometry is a bit rusty but your correct the Strelock Pro App does exactly that as your selecting what the angle looks like by dragging the target up or down it is giving the COS of the angle.
when you say observed many will take this to mean using a laser range finder or scope retical
you would of course on a 373 yard target @ 45* angle also be 373 yards above your target and optically the hypotenuse of your triangle would be observed at 527 yards.
so you would fist need to figure out actual distance to your target and not optical distance to your target.
Quote from: TrapperPete on September 12, 2018, 03:28:46 PM
when you say observed many will take this to mean using a laser range finder or scope retical
you would of course on a 373 yard target @ 45* angle also be 373 yards above your target and optically the hypotenuse of your triangle would be observed at 527 yards.
so you would fist need to figure out actual distance to your target and not optical distance to your target.
True, I use a laser range finder.
You would be above
or below your target. If you wanted to know how high you were above or below the target, you would need to use the sine function values. Not what were interested in right now.
Not really, actual distance to the target is what cosine (angle) X optical distance would give you.
So as to avoid semantic differences, to me, actual distance is distance over the ground, perpendicular to pull of gravity. Optical distance is what I get from my laser. Or in simpler terms, distance from my eyeball to the target (what you call hypotenuse). Of course, some lasers will do the math for you and give you ground distance directly.
Using the right triangle example, the hypotenuse is what I see, eyeball to target; I get that from the range finder. What you are trying to determine is the side of the triangle opposite the hypotenuse. For the angle, an app to your smart phone will tell you.
You can be shooting uphill or downhill and it doesn't matter.The value of the correction will be the same. From my previous example, for a zero elevation angle, my ballistics calculator would give me 6.09 MOA up from my 100 yd zero for a target 373 yds away. For a 45 degree angle the range would be 264 yds and my ballistics calculator would tell me my correction is 2.99 MOA up from my 100 yd zero. I can't dial small fractions, so I would use 6 MOA and 3 MOA. If time was of the essence and I didn't have time to dial a correction, Aim low like PHenry posted. How much, you decide.
Clear as mud?? Lomshek was right, for Appleseed, don't worry about angles.
aj
To add another fun wrinkle, if it hasn't been mentioned yet:
Use the shortened / calculated distance when figuring your elevation adjustments needed, but use the full (actual) distance when figuring for your wind hold-offs. Whether you're shooting horizontally, vertically, or anywhere between, the bullet still has to travel the full distance to the target, and will be influenced by wind the whole way there.
exactly it could become it's own weekend course. If you could find a place to shoot it.
possible prerequisites:
you have twice scored Rifleman KD
you have collected solid numbers for your round and rifle from 100-500 yards
bring your scientific calculator with and have completed the refresher worksheet on geometry.
do you know of a place with enough elevation to hold such a Mountain Mans Rifle event?
but really for inside 250 yards with a modern rifle , the change isn't that big and for AS KD purposes they are already overwhelmed with information and a lack of time , just introducing the concept with up or down it reduces the correction needed.
Quote from: PHenry on September 09, 2018, 02:49:09 PM
After I cover angle shooting during a KDC class, I offer the simple method - when shooting uphill or downhill, aim a bit low. The angle has to be fairly extreme for a serious correction from what I am told by thems who have actually done it. Like S22 stated, here in what was once the very flat sea floor, we don't get much practice. ^-^
well said