Somebody please school me!
- Thread starter Dave T
- Start date
higher is the theory in both uphill and down hill shots. At least that is the way I have been told.
Erik Cortina
Team Lapua Brux Borden Captain
At that range I would hold dead on. Not enough distance to matter.
At longer shots, hold low.
At longer shots, hold low.
If it is just a slight angle shoot as if it is flat. If it is a steep angle you may need to hold lower depending on your "max point blank range" (a relation involving the size of the target zone and other variables.) The difference will be more severe with longer shots. The steeper the angle the lower the "hold under."
That would depend on your zero range, that you did not mention, and also what is moderate? Cosign the angle and multiply by straight line measurement, hold for that distance(which is shorter) and send it. It don't get much easier. I shot a Whitetail over bait last week at a lasered 61 yards from a elevated stand. The angle to the target(Look angle) per my Leica CRF 1600 was -5 degrees. Did the math(after the fact) and it was 58 yards. Held 100 yd. dot on the Medulla Oblongata and broke the trigger, Deer jerky in the forecast! ;D
Keith Glasscock
Gold $$ Contributor
For 200 yards lasered,
45 degrees - (darn steep - 424 feet above or below the target) 141 yards trajectory- hits 1 inch high (or less) for most rifles
30 degrees - (still darn steep - 300 feet above or below target) 173 yards trajectory - within half an inch with most rifles
10 degrees - (what you are probably asking about - 100' above or below target) - 196 yards trajectory - dead on.... Your laser probably isn't that accurate anyway
The guys that advise a dead-on hold absolutely know what they are talking about. You would only hold off at that short of a range if you were trying to hit something really small (like a sage rat or prarie dog laying down).
To get a great estimate of the trajectory range for any shot, use:
COS(look angle) * Laser range
Other option is to get one of the fancy laser range finders that do the work for you. Special situations also apply such as a high treestand over flatish terrain. Just laser landmarks from the base of the tree and you have the proper trajectory range without having to do the math. Same goes for ranges derived from maps or satelite photos - they are already flat.
45 degrees - (darn steep - 424 feet above or below the target) 141 yards trajectory- hits 1 inch high (or less) for most rifles
30 degrees - (still darn steep - 300 feet above or below target) 173 yards trajectory - within half an inch with most rifles
10 degrees - (what you are probably asking about - 100' above or below target) - 196 yards trajectory - dead on.... Your laser probably isn't that accurate anyway
The guys that advise a dead-on hold absolutely know what they are talking about. You would only hold off at that short of a range if you were trying to hit something really small (like a sage rat or prarie dog laying down).
To get a great estimate of the trajectory range for any shot, use:
COS(look angle) * Laser range
Other option is to get one of the fancy laser range finders that do the work for you. Special situations also apply such as a high treestand over flatish terrain. Just laser landmarks from the base of the tree and you have the proper trajectory range without having to do the math. Same goes for ranges derived from maps or satelite photos - they are already flat.
Right idea but the gravitational pull is constant for all practical purposes. In this case, the projectile is subjected to the force of gravity for a shorter period of time than it would be if fired horizontally. It travels the same line of sight distance, but not the same horizontal distance.
it seems a lot of ideas but some not so good
this from Sierra data base:
5.2 Effects of Altitude and Uphill/Downhill Shooting
Sierra's computer program for exterior ballistics calculates precise bullet trajectories at any altitude and for any firing angle, uphill or downhill. The program not only accounts for the altitude of the shooter, but it also calculates the change in drag that occurs as the bullet changes altitude after it leaves the muzzle. With this capability we can see exactly what effects altitude and firing angle have on the trajectory of any bullet.
It is reasonably easy to calculate how much higher a rifle will shoot for any given elevation angle. To do this, we need to know the bullet drop versus range for the load used, and we can find this in the Ballistics Tables for any Sierra bullet. Let d be the bullet drop at any range R from the muzzle. (In this calculation we are only concerned with the amount of the drop; the minus sign in front of the drop numbers in the Ballistics Tables can be neglected.) The following table shows how much higher the bullet will shoot when aimed either uphill or downhill than it will when fired on a level:
Increase in
Elevation Angle Bullet Path Height
+/- 5 degrees .004 d inches
+/- 10 .015 d
+/- 15 .034 d
+/- 20 .060 d
+/- 25 .094 d
+/- 30 .134 d
+/- 35 .181 d
+/- 40 .234 d
+/- 45 .293 d
+/- 50 .357 d
+/- 55 .426 d
+/- 60 .500 d
To use this table, we first look up the drop d for each value of range for our load in the Ballistics Tables. Then, we calculate the increase in bullet path height for each elevation angle of interest using the multiplying factors in the table above. This tells us how much higher the bullet will shoot than it will for level fire at each value of range and for each elevation angle we wish to consider. Finally, we may add this increase to the bullet path height for level fire (from the Ballistics Tables) to get a new bullet path height at each elevated firing angle.
As an example of this procedure, and also to show how much even a relatively flat-shooting cartridge can be affected by elevated firing angles, the calculations in Table 5.2-3(rifle) Table 5.2-3(handgun) have been performed for a .270 Winchester firing the 130 grain spitzer boat tail bullet at 3000 fps muzzle velocity. The bullet drop data at the top of Table 5.2-3(rifle) Table 5.2-3(handgun) are taken from the Ballistics Tables for the 130 grain .270 spitzer boat tail bullet. Bullet path data for the rifle zeroed in at 200 yards are also listed so the new bullet path can be calculated for each elevation angle.
To understand how the numbers in Table 5.2-3(rifle) Table 5.2-3(handgun) are calculated, let's look at the case where the firing elevation is +/- 30 degrees and the slant range is 400 yards. At this elevation angle the increase in bullet path height is 0.134 times the drop at each value of range. At 400 yards the drop is 37.56 inches, so the increase in bullet path height is 0.134 x 37.56 = 5.03 inches. So, if the shooter aims at a game animal 400 yards away or up or down a 30 degree slope, he has to remember that his bullet will shoot about 5 inches higher than it would on the level. With his rifle sighted in for 200 yards, his bullet path would be 19.47 inches below his line of sight at 400 yards for level fire. So, if he corrects the bullet path for the 30 degree angle, his new bullet path will be 14.44 inches below his line of sight at 400 yards, instead of 19.47.
It is clear from Table 5.2-3(rifle) Table 5.2-3(handgun) that steep elevation angles have important effects for this .270 Winchester load, and the steeper the angle the shorter the range where the effect becomes important. It turns out that steep elevation angles are important for nearly all hunting rifles. To cite just a few others, when fired uphill or downhill at a 45 degree angle, a .22-250 with the 55 grain spitzer bullet at 3700 fps muzzle velocity will shoot 4.2 inches high at 300 yards; a .300 Winchester Magnum with the 180 grain spitzer boat tail at 3000 fps muzzle velocity will shoot 5.6 inches high at 300 yards; and a .30-30 with the 150 grain flat nose at 2200 fps will shoot 5.9 inches high at 200 yards. The importance of understanding and compensating for firing elevation angle effects is pretty clear from these figures.
Bob
this from Sierra data base:
5.2 Effects of Altitude and Uphill/Downhill Shooting
Sierra's computer program for exterior ballistics calculates precise bullet trajectories at any altitude and for any firing angle, uphill or downhill. The program not only accounts for the altitude of the shooter, but it also calculates the change in drag that occurs as the bullet changes altitude after it leaves the muzzle. With this capability we can see exactly what effects altitude and firing angle have on the trajectory of any bullet.
It is reasonably easy to calculate how much higher a rifle will shoot for any given elevation angle. To do this, we need to know the bullet drop versus range for the load used, and we can find this in the Ballistics Tables for any Sierra bullet. Let d be the bullet drop at any range R from the muzzle. (In this calculation we are only concerned with the amount of the drop; the minus sign in front of the drop numbers in the Ballistics Tables can be neglected.) The following table shows how much higher the bullet will shoot when aimed either uphill or downhill than it will when fired on a level:
Increase in
Elevation Angle Bullet Path Height
+/- 5 degrees .004 d inches
+/- 10 .015 d
+/- 15 .034 d
+/- 20 .060 d
+/- 25 .094 d
+/- 30 .134 d
+/- 35 .181 d
+/- 40 .234 d
+/- 45 .293 d
+/- 50 .357 d
+/- 55 .426 d
+/- 60 .500 d
To use this table, we first look up the drop d for each value of range for our load in the Ballistics Tables. Then, we calculate the increase in bullet path height for each elevation angle of interest using the multiplying factors in the table above. This tells us how much higher the bullet will shoot than it will for level fire at each value of range and for each elevation angle we wish to consider. Finally, we may add this increase to the bullet path height for level fire (from the Ballistics Tables) to get a new bullet path height at each elevated firing angle.
As an example of this procedure, and also to show how much even a relatively flat-shooting cartridge can be affected by elevated firing angles, the calculations in Table 5.2-3(rifle) Table 5.2-3(handgun) have been performed for a .270 Winchester firing the 130 grain spitzer boat tail bullet at 3000 fps muzzle velocity. The bullet drop data at the top of Table 5.2-3(rifle) Table 5.2-3(handgun) are taken from the Ballistics Tables for the 130 grain .270 spitzer boat tail bullet. Bullet path data for the rifle zeroed in at 200 yards are also listed so the new bullet path can be calculated for each elevation angle.
To understand how the numbers in Table 5.2-3(rifle) Table 5.2-3(handgun) are calculated, let's look at the case where the firing elevation is +/- 30 degrees and the slant range is 400 yards. At this elevation angle the increase in bullet path height is 0.134 times the drop at each value of range. At 400 yards the drop is 37.56 inches, so the increase in bullet path height is 0.134 x 37.56 = 5.03 inches. So, if the shooter aims at a game animal 400 yards away or up or down a 30 degree slope, he has to remember that his bullet will shoot about 5 inches higher than it would on the level. With his rifle sighted in for 200 yards, his bullet path would be 19.47 inches below his line of sight at 400 yards for level fire. So, if he corrects the bullet path for the 30 degree angle, his new bullet path will be 14.44 inches below his line of sight at 400 yards, instead of 19.47.
It is clear from Table 5.2-3(rifle) Table 5.2-3(handgun) that steep elevation angles have important effects for this .270 Winchester load, and the steeper the angle the shorter the range where the effect becomes important. It turns out that steep elevation angles are important for nearly all hunting rifles. To cite just a few others, when fired uphill or downhill at a 45 degree angle, a .22-250 with the 55 grain spitzer bullet at 3700 fps muzzle velocity will shoot 4.2 inches high at 300 yards; a .300 Winchester Magnum with the 180 grain spitzer boat tail at 3000 fps muzzle velocity will shoot 5.6 inches high at 300 yards; and a .30-30 with the 150 grain flat nose at 2200 fps will shoot 5.9 inches high at 200 yards. The importance of understanding and compensating for firing elevation angle effects is pretty clear from these figures.
Bob
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.