W
wpbram
Guest
When shooting from up hill to down hill will my round hit same spot as at the range on level ground?
D. E. Laneer
New member
Theoretically it should hit higher on the target. The distance and angle you shoot up or down
will determine the change of impact.
will determine the change of impact.
Dusty Stevens
Hollow Point Dispenser
Boy those slope angles really throw a wrench into shooting systems.
Hunter
Chasin' the Sunset
I think this is correct: assuming the horizontal distance is the same the POI will be the same; however, if the line-of-sight distance is the same the downhill shot will have less horizontal distance -- thus, the POI will be higher.
The answer is NO. It doesn't matter if you're shooting uphill or downhill your line of sight is the HYPOTENUSE of a triangle, because the hypotenuse is always longer than the base your bullet time of flight will be longer and your point of impact will be LOWER.
Dick
Boyd Allen
Active member
The horizontal difference rather than the length of the line of sight is what determines bullet drop. When shooting both uphill and downhill the horizontal distances are shorter than the lines of sight. My friend has a fancy (and expensive) rangefinder that automatically senses angle when readings are taken and compensates when calculating scope settings. There are also rifle attachments called angle cosine indicators that give you a number that when multiplied by your line of sight distance, gives you the horizontal distance.
Hunter
Chasin' the Sunset
Quoting form Hornady Handbook of Cartridge Reloading, Sixth Edition, Volume 2, page 993, "
Gents,
With a bullet that is fired horizontal with Mother Earth, gravity acts perpendicular to the bullet trajectory throughout its flight to the target. When we shoot uphill or downhill, gravity no longer acts perpendicular to the bullet path.
Shooting uphill or downhill at a 15 degree angle, only .96% or so of gravity is trying to displace the bullet the from the line of bore. Since, by definition, bullet drop is bullet displacement perpendicular to the line of bore, the bullet would drop about 4% less when shooting uphill/downhill at a 15 degree angle. If it drops 4% less, it will hit 4% higher on the target.
To solve the above, you need to know your line of sight distance, the up/down angle, and the cosine of that angle. Take your line of sight distance...let's say 300 yards...and multiply by .96, this being the cosine of 15. 300 x .96 = 288. 288 being the yardage one should hold for. Probably not a shot killer on a deer, but the bullet will strike a bit high if you use your 300 yard hold.
Let's make it a 45 degree angle: cos (45) is about .70. 300 x .70 = 210. If your using the line of sight distance (300) for this shot, you're gonna wound or miss that deer.
If you know the map distance/horizontal distance, regardless of your line of sight distance, that is the yardage you should hold for.
You do use the line of sight distance when figuring your windage holds, as the wind will be affecting the bullet over this distance, not the map/horizontal distance.
Justin
With a bullet that is fired horizontal with Mother Earth, gravity acts perpendicular to the bullet trajectory throughout its flight to the target. When we shoot uphill or downhill, gravity no longer acts perpendicular to the bullet path.
Shooting uphill or downhill at a 15 degree angle, only .96% or so of gravity is trying to displace the bullet the from the line of bore. Since, by definition, bullet drop is bullet displacement perpendicular to the line of bore, the bullet would drop about 4% less when shooting uphill/downhill at a 15 degree angle. If it drops 4% less, it will hit 4% higher on the target.
To solve the above, you need to know your line of sight distance, the up/down angle, and the cosine of that angle. Take your line of sight distance...let's say 300 yards...and multiply by .96, this being the cosine of 15. 300 x .96 = 288. 288 being the yardage one should hold for. Probably not a shot killer on a deer, but the bullet will strike a bit high if you use your 300 yard hold.
Let's make it a 45 degree angle: cos (45) is about .70. 300 x .70 = 210. If your using the line of sight distance (300) for this shot, you're gonna wound or miss that deer.
If you know the map distance/horizontal distance, regardless of your line of sight distance, that is the yardage you should hold for.
You do use the line of sight distance when figuring your windage holds, as the wind will be affecting the bullet over this distance, not the map/horizontal distance.
Justin
Doug Casner
New member
high hits
I don't know the laws of shooting up or down but I missed a nice muledeer buck in Colorado one time with a .270 about 250 yds. downhill from me 5 times. Every shot went over his back. I was standing there with a empty rifle and he was still running. Im not a good shot but I think Id got a piece of him at 250 on flat ground. Doug
I don't know the laws of shooting up or down but I missed a nice muledeer buck in Colorado one time with a .270 about 250 yds. downhill from me 5 times. Every shot went over his back. I was standing there with a empty rifle and he was still running. Im not a good shot but I think Id got a piece of him at 250 on flat ground. Doug
Hunter
Chasin' the Sunset
Even JOC might have missed an off-hand shot at a running deer 250 yards away.
Doug Casner
New member
high hits
It was just me. Im no Jack Oconner. thanks for setting me straight.
It was just me. Im no Jack Oconner. thanks for setting me straight.