Do you use an Angle Cosine Indicator (ACI) for uphill/downhill shots?

[T3-OleMan]

Yes, but not on my 338 yet, only got a 2% chance at anything over 300yds and I'm not geared up for anything but quick shots with Zero at 200. If I ever go Long Time-Long Range U-BET and will get the other knobs to go with it.

Made my own in 1997 from $3 worth of school supplies and a broken level's bubble, for slinging 2114s at ELK in Colorado's Weminuche Wilderness. We never got on 60 deg slopes, about 45 < 50 is all we could hold on to, but the physics of the 60yd shot on the 60deg slope requiring the 30 yd pin left me with a healthy respect for gravity at long distance.

Can't beat knowing where your projectile is going to be at all distances.
One of them " Don't Screw Around With Mother Nature things"!......

 

[nfhjr62]

Just purchased a Mil Dot master comes with an angle cosine on the back of unit just need piece of string and small weight to use.

 

[Long Dog]

I have and Angle Degree Indicator on mine, since my ballistic computer takes degrees and not the Cosign. I have a angle/Cosign conversion chart on my range card in my stock pack for the times when I don't have my computer with me.

 

[paphil]

Cosine of angle
5 deg - .4 /100 .996
10 deg - 1.5/ 100 .985
15 deg - 3.5/ 100 .966
20 deg - 6 / 100 .940
25 deg - 9.5/ 100 .906
30 deg -13.5/100 .866
35 deg -18 / 100 .819
40 deg -23.5/100 .766
45 deg -29.5/100 .707
50 deg -35.5/100 .643
55 deg -42.5/100 .574
60 deg - 50 / 100 .500

A little chart that I plastic coated and cary in my wallet. My binoculars give the angle and then I use the chart .Works for yards or meters The first column is degrees, the second is what must be subtracted for each 100 of distance. For example, a 600 yard shot at 20 degrees, would be 6 X 600 or 36 off the total. Set the scope at 600 -36 = 564. A little math is needed but sure beats guessing! The last column is the cosine and can be directly multiplied by the measured distance to give the hold distance. Using the same 600 yards X .940 = 564.

 

[985]

I use it... I Always use it... There aren't any batteries to fail; no electronics to fail, its' always right where you put it, On the Gun; and it is also in use by every military under the Nato umbrella including the US Army, US Marine Corps, US Navy, and the US Air Force.

 

[Pistol packer]

i have always resisted anything extra to put on my rifle. the other day got a scope level and put it on my .25 " 300 WM model 70 w/lilja barrel. thought if that little item can help this one, then i would put it on all the long range guns. first 5 shot group went into the low 1's. ouch.....all you crazy guys were right.
same for the angle indicator. always held low and never missed. only shot once over 500 yards tho. and that was about 1300 or so and got lucky and saw my impact and adjusted. so....am not going to even wait. going to get mine stat. like the android idea, several around here have one, but i hunt in areas that cell phones dont work and if it gets cold enough, the cell dont work anyway, batteries can go dead, lost, unit get broken etc. like to keep it simple.

 

[Triple BB]

I copied this from a write up on another site. Still trying to figure what he's saying. Wish the author would've include a sample diagram. Anyone use this method? If so, how about more detail.

"Another Rule-of-Thumb, suggested to me by Sergeant Neal Terry, a longtime
sniper instructor and police SWAT sniper, is to draw an invisible vertical line
through the up or down target, and where this line intersects the earth's surface,
range it! Disregard the angle, ignore the direct distance from muzzle-to-target,
concentrate only on adjusting elevation for the distance to where that vertical line
touches the earth. Compensate for that distance, aim dead-on and fire. We've
worn out several pads of paper comparing Neal's math to other kinds of up/down
calculations - it works and it's the essence of simplicity!"

 

[Eaglet]

Don't get it!
Target is already in the ground, makes no sense to draw a vertical line through the target and onto the ground... I must really be getting old...

 

[985]

Eaglet... I'm sorry to hear that you aren't aging so well.

 

[Eaglet]

Trying to do better but it ain't easy!

 

[T3-OleMan]

lightbulb
Could it be so simple as this would eliminate the false reads of the BIG FAT Divergence #s (ie. BEAM SIZE) when they sometimes pick a limb or a rock in front of or behind the target? He could be going vertical to the nearest clean absolute earth?????? Just a thought.

Divergence #s (ie. BEAM SIZE)
Swarovski Laser Guide 8x30.............................2.5H x 2.5W millirads

Zeiss Victory 8x26 T* PRF ...............................2.0H X 4.0W.Millirads

Leica CRF 1600 ..............................................0.5H * 2.5Wmillirads

I have had all 3 one time side by side but, haven't enough data to give you any solid advice. BUT, I own a Leica 1200 CRF and a Swaro laser guide 8x30. I had them side by side a couple days ago ranging speed goats in mid day light, flat ground. Rangefinders were on a solid bench on a rest. Goats were 1031 yards away. The only way I could know, was the Lieca hit them several times. Swaro would not touch them. But the Swaro would range the road bank at 1250 yards behind them. Like mentioned before, watch that beam devergence!! It cost me a trophy deer last year. I think they both have merit, but on flat ground I like the Leica 1200 CRF. If you are ranging trees, rock walls, or into hillsides, the Swaro will range farther. If you are ranging game on flat ground, DON'T over look the Lieca 1200 CRF.

Jeff

http://www.longrangehunting.com/forums/f22/what-best-range-finder-27247/index2.html

After talking to Jeff, back in June I think, this caused me to go with the Lieca 1600 CRF, for my application!

 

[985]

Eaglet: It's all about Love.

T3-OleMan: LRF's... What a topic. Leica'a PLRF ($10,000.00) is my first choice.

 

[985]

Eaglet: It's all about Love.

T3-OleMan: LRF's... What a topic. Leica'a PLRF (about $10,000.00) is my first choice.

 

[Gone Ballistic]

I have been using Nightforce's ADI (angle degree indicator) every since purchasing Nightforce scopes. I don't know which is better as the Nightforce program uses either in computing where to set the scope. They are a valuable tool in long range shooting and I use them on two different rifles. My .22-.250 VZ 550 and 300RUM custom.