Ian, I need your help, please?

[Guest]

Warren-- Copy the tables in S1's post on A.R. Tactical. The whole proces is there, including the correction table in 5 degree increments, and the equations.
http://artactical.com/eve/ubb.x?a=tpc&s=692600194&f=701602405&m=859609536

 

[Warren Barrett]

Antslayer, I`ve already copied those, but the shot angles are in 10 degree incriments up to 40 degrees.
Do you think splitting the difference would be close enough?

 

[Guest]

Warren-- This should fill in some of the blanks, I hope this helps.

Correction factors:

5 degrees = .0038

15 degrees = .0341

25 degrees = .0937

35 degrees = .1809

85 degrees = .9128

90 degrees = 1.0

As you may see, the changes are small but become more and more critical as range increases. I admire your determination to get it right the first time. You will get a lot of advice from people about how to do things. What most of these advice givers do not understand is the relationship of multiple errors and how several small errors will add up to a big MISS! You may have read a recent post about mil radian spacing, and one advice giver wrote that using an 'estimate' would suffice. Try to imagine a simple shot from 1200 yards with a 30 degree incline and a 4.7 percent ranging error, now....compound that error with the error from using a ACI and the wrong inclination formula. Both errors could sum and cause you to shoot low. Which will result in you shooting so FAR UNDER the target you will be left scratching your head. This is why guys wind up taking "spotter shots". Their methods have these little flaws in them, and they can not understand the interaction of all of the small errors. OOPS....MISSED AGAIN!

Not all errors sum, they can cancel eachother out occasionally, and you could get lucky.....does everybody FEEEEEEEEEL LUCKY? I think in the real world, every one feels Mr. Murphy's presence. What Teo said about the wind is true, but you can learn to deal with it. One shot kills at 1,000 yards are common with todays technology, even in mountainous terrain. We hunted in Utah last year, and had a shooting contest in between Elk and Mule deer season. One shot at an Elk sized torso at 500 yards, if you hit, you are still in, if you miss, you are out. Out of 12 guys in the contest, 3 made it to 900 yards with hits at that distance. 1 of the guys had no formal training, just a car salesman from Salt Lake. The two with training and experience went to 1400 yards, and the winner went to 1500, and could have gone further, just ran out of time.

P.S. The error correction factor for any angle is 1.0 - the angle's cosine.

Keep shooting with precision, and keep thinking with precision, you will shoot farther and straighter than most. I think CrowMag says it best.....

"If you think something is not possible move out of the way so the ones that are doing it can "

[ 10-09-2004: Message edited by: Antslayer ]

 

[Warren Barrett]

Antslayer, as you said, ocassionally Murphy`s law does get us all, but knowing how to do something and not knowing makes all the difference in the world. The more we can learn about what we`re doing, the more we can do with it and I just love that.
As already stated, I`m a newby to this longrange game in mountainous terrain and I very much appreciate all of the replies. I can now get started with more confidence.

thanks again, Warren

 

[Scol]

Hi Warren. This may be a bit late for your trip but others may find this useful. The data below can be used to find the horizontal distance to the target from the incline angle and slope (measured) distance.

0 deg (horiz.), multiply slope distance by 1
5 deg, multiply slope distance by 1
10 deg, multiply slope distance by 0.98
15 deg, multiply slope distance by 0.97
20 deg, multiply slope distance by 0.94
25 deg, multiply slope distance by 0.91
30 deg, multiply slope distance by 0.87
35 deg, multiply slope distance by 0.82
40 deg, multiply slope distance by 0.77
45 deg, multiply slope distance by 0.71
50 deg, multiply slope distance by 0.64
55 deg, multiply slope distance by 0.57
60 deg, multiply slope distance by 0.5

A useful instrument for measuring angles is a clinometer. Some of the Silva compasses have these built in, while Brunton makes one called the CM Clinomaster and Suunto also makes a good one called the PM-5/360 PC. The used Suunto ones sell on e-bay for about $50.

Hope this helps. I was wondering when that engineering degree would come in handy.

 

[Warren Barrett]

Thanks Scol.
Yea it`s a little late for the trip, but it`ll be helpfull information in the future.

thanks a lot, Warren

 

[700]

Warren

If you give me any ballistic info that you might have to hand, I can make a ballistic chart for you.

Do you have any idea what altitude you will be shooting at in the rockies.

I will email you sample copy.

The Silva/Bruton Horse Shoe Compass with Inclinometer is a nice piece of kit.

Rgds

700

 

[700]

Warren

Email sent to Ricky.

Rgds

700

 

[Warren Barrett]

Thanks 700 for wanting to help. We`ve been home now from our trip for about 2 weeks.
I`m sorry about your e-mail to me. I deleted it before I found your post on this board. My server said to delete it if I was not sure of the e-mails origin. It referred to a 6.5x55 and I don`t own one, so I was a little scepticle to open the attachment. We`ve had some mean viruses in the past, so I don`t open everything now.
If you want, you could do a chart for me with the following information so I could do a comparison with mine whenever time allows.

1) 220gr. Sierra MK
2) 3125 fps at 15 feet from muzzle
3) 2.25 inches scope height above bore line
4) 300 feet altitude
5) 60 degrees F.
thanks, Warren.

 

[700]

Warren

I have sent you a copy of yesterdays email.

I realised too late that the hunting trip was last month, not this month.

Regards

700

[ 11-03-2004: Message edited by: 700 ]

 

[700]

Warren

Just sent you the charts.

Rgds

700

 

[Warren Barrett]

700, thanks for the charts. I`ve tried to take a look at them, but my computer has a mind of it`s own sometimes seemingly. Will eventually get to check them out.
and again, thanks, Warren

 

[700]

Warren

Let me know how you get on with the ccharts. They were calculated using the ballistics coefficients on the Sierra Website. If you have a set of real world drops I might be able to add these to the ballistic stew.

Next time you are hunting in the rockies I will have you armed with a chart which will allow you to zero at your local range and then take angled shot at high altitude.

Rgds

700

 

[Warren Barrett]

OK 700. That sounds great. It`ll be in January at the earliest before I can compare the charts to real world data.
Thanks again.
Warren