Elevated or declined targets?

[CoyoteJack]

I saw a segment on a Outdoor channel show that went over the basics of bullet drop when shooting uphill or downhill.

Basically they claimed the results where the same, since you are effectively shooting along the long leg of a right triangle the distance is actually shorter than if on level ground and your point of impact is actually higher than if on level ground, regardless of whether it is an up or downhill shot.

My longest shot hunting was close to 300 paces away and just guessing some 300 foot of drop (on a ridge shooting down into a power line clearing in a valley). I didn't want to risk shooting over the buck so I held the crosshairs right on the spine. My .308 should drop around 8" at that distance and I hit the buck nearly dead center just behind the front shoulder. I'm unsure though if the drop would have been much different on level ground.

I've never shot uphill. Most tree stand hunting on level ground with a rifle doesn't provide enough elevation to matter ballistically.

So does anyone have much experience with this? Does the angle of trajectory itself not effect bullet drop?

[markheck1]

Interesting Question....

Whether the force of gravity would affect something that small in mass in uphill or downhill shots......

I'll have to do some research!

[Tomcat088]

What you heard is in fact correct. Shooting uphill or downhill will make it seem like you're shooting "high". Most of the time this isn't a huge issue if the angle isn't significant, or if the distance isn't that far (I know alot of people in PA don't shoot much over 100 yards). If you ever go on a hunt in the mountains, or are shooting from elevated or lower down positions, this can definately have a huge impact, especially at a distance. As the ranges get further and the angles increase, the numbers can change ALOT. You will see shooters with tools like the angle cosine indicators by badger ordnance, you can see a picture here (click on the indicator) http://www.badgerordnance.com/produc...id=accessories. This helps give them an accurate reading to do calculations with. I'm going to include 2 links here that do a decent job without going into great detail about shooting on angles. In the second the guy actually talks about an angle cosine indicator. The second article is actually slightly better because it actually talks about some of the math and how you can make calculations to correct for this data. In order to do this though, you must know the angle that you're shooting at. http://www.wildsheep.org/magazines/a...l_shooting.htm
http://www.snipertools.com/article5.htm

Some of the newer range finders actually do the calculations for you and give you a "corrected" number as your yardage. The other day I saw a cheap cosine indicator that you basically put on the bottom of your barrel and a hanging weight on a string told you the angle measurement. That's the cheapest way to do this, and it is still accurate. I'll see if I can find a link in case some of you are interested in a cheaper method to measure angle of inclination. If you have any other questions, please feel free to ask and I'll be happy to help in any way that I can.

Edit: The tool that I was thinking about is mentioned in the first article and it's called the "slope doper". I have heard that it is a cheap and accurate way to measure angle of inclination. The numbers on it are actually the cosine numbers that you multiply your estimated or undoctered ranged number by in order to get the "corrected distance value". Here's a link to a guy doing a review on it. http://www.snipercountry.com/InReviews/SlopeDoper.asp

[whoshisface]

I'm a little confused..

Gravity neither increases nor decreases based on angle?

Perhaps a downward shot would drop slower or not as much because gravity is also pulling it forward increasing bullet speed so long as terminal velocity hasn't been reached?

I'm just a little lost here.

Sounds like a damn interesting conversation though...

[Brick]

Gravity acts on your bullet only over the horizontal portion of your shot. So if you are shooting at a target at a slope distance of 500 yards away and it is 300 yards higher than you, its' horizontal distance is 400 yards and gravity will act on your bullet only for that distance. So when you shoot at your target you use the hold-over or sight setting that you'd use for a 400 yard shot.

[Tomcat088]

LOL, you beat me to it brick, good post. Yes, just as he said exceltoexcel. The bullet may actually travel 500 yards, but it only affect the horizontal portion of the distance that the bullet travels. Depending on the angle, this might only be 400 yards. The gravity always acts exactly the same on the bullet from the moment that it leaves the barrel. So really, you just have to know the bullet for the horizontal distance that the bullet travels. The bullet drop will be the same for 400 "horizontal yards" whether you are shooting 400 yards perfectly level, or 400 yards on an angle (which would really look further because your eyes see the hypot. of the triangle, the long side which is the actual distance) BUT gravity will only affect the horizontal distance.

[markheck1]

Wow...that's pretty wild!

[CoyoteJack]

Wow...that's pretty wild!

Agreed

I understood the geometry of the shot but not the physics.

[Tomcat088]

Hey Coyotejack, I sent you a PM, maybe I can help. Check your PM and if you like, I'll be waiting in chat, maybe I can help.

[CoyoteJack]

I've never shot any really long distances. Years ago when I started hunting I dialed in my .308 so that I was 2" high at 100 yards. That allows me to basically point CoM on a deer out to 200' without trying to figure out drop. Longer than that and I raise it abit. I've never had a shot that required holding over a deer.