One of my favorite topic [img]images/icons/smile.gif[/img] [img]images/icons/smile.gif[/img]
There are at a minimum three common methods to resolve the uphill/downhill trajectory problem(s).
Here's a link to a recent article on this subject.
For me it boils down to two distinct issues... does the shooter have the option to fire a round and then correct for a second round hit. If there is no option for a second round hit then an indepth understanding is probably desired.
Just to give a little hint of the "unseen" problems... What is your rifles' zero range? Is this the range you correct for the angled/inclined fire from? In other words...the target it 500 line-if-sight yards at 45 degrees (just to make it easy) 500 * .707 (the cosine of 45) = 353 yards... standard come-up fro 353 yards is about 5.5 MOA for a 308 vice the 10.5 or so 500 yard come-up... 5 MOA diff or a miss high by about 17.5 inches. WHAT about the 3.5 to 3.75 MOA of elevation already in the system to zero the rifle at 100 yards...we don't correct this value and it is important. To see how large this error could be we only need to think about a shot straight up or straight down. Zero the rifle at 100 yards (scope set to -0-). Find a tall cliff (El Capitan or some such) and shoot straight down....where will the bullet hit? It'll hit away from our point of aim in the 12 o'clock direction (relative to the rifle at time of firing the round) by the amount of correction required for the 100 yard zero (3.5 MOA for a 308 type rifle)...that little bit (3.5 MOA) can cause a fair miss at based on long range and big angles or big angles and small targets.
Sorry... told you this was a favorite of mine.
[ 09-18-2003: Message edited by: Dave King ]