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How accurate are angle cosine indicators?

 
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  #1  
Old 11-25-2003, 08:24 PM
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Location: McKinney TX
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How accurate are angle cosine indicators?

How accurate are angle cosine indicators?

I remember one of my sniper courses covered this and we only used angle cosines for short ranging out around 300 yards max. If the shots were over 300 yards, the angle cosine werenít very accurate as they only told you the angle distance, but it doesnít take into account the time of flight of bullet and the additional drop the bullet experienced.

Itís been a long time since that training and living and shooting in Texas we donít really have angle shots. Not many big hills here.

Anyoneís thoughts on the subject?
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Mathew 5:16

Distance is not an issue, but the wind will make it interesting!
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  #2  
Old 11-25-2003, 11:30 PM
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Re: How accurate are angle cosine indicators?

Jeff,

I'm going to get one and test it out this winter. I had the same question too.

We got some good hills her for testing it. [img]images/icons/grin.gif[/img]
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Old 11-26-2003, 09:23 AM
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Re: How accurate are angle cosine indicators?

Made one from a Protractor and small bubble level. Attached it to the straight edge of the stock on the big 338/416 Rigby IMP.
It works fine.

Have four sets of drop charts I use that are also attached to the side of the stock. One at level shooting, one at 10 degrees another at 20 degrees and one at 30 degrees.
There is a difference in drops especially at every 10 degree increment from a level plane.

We find that, a spotter shot fired first will eleminate most any variance in drop or windage though as you can adjust to the impact and then swing back to the animal and kill it quickly. In most cases we don't use the incline indicator.

For those wanting to make a first shot hit at extreme range, you better know the wind patterns real good and this usually takes many years to "try" to figure out. Most never do figure it out.
The elevation indicator won't help a bit if a person don't know the wind "first".

Later
DC [img]images/icons/smile.gif[/img]

[ 11-26-2003: Message edited by: Darryl Cassel ]
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Old 11-26-2003, 03:47 PM
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Re: How accurate are angle cosine indicators?

For those wanting to make a first shot hit at extreme range, you better know the wind patterns real good and this usually takes many years to "try" to figure out. Most never do figure it out.

It done successfully all the time, it just takes practice, some more than others. [img]images/icons/wink.gif[/img]

Look at the aggs of the top scores at 1000 yards and you'll see who capable of keeping 'em all on POA for 10 shots, and who isn't.
They aren't all shot in perfect conditions either.


The elevation indicator won't help a bit if a person don't know the wind "first".

Actually I think you'd figure the static incline effect "first", then the wind speed and effect "immediately" preceeding the shot. [img]images/icons/wink.gif[/img]

Knowing the angle effect is just as important as knowing how small of groups you're capable of printing on POA at what ever range you shoot, by what ever methed you use too. If it ain't smaller than kill zone size from POA, it ain't practical and is nothing more than a wish.
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Old 11-26-2003, 04:08 PM
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Re: How accurate are angle cosine indicators?

Brent

I don't think you have ever fired a 10 shot 1000 yard match so the procedure is probably new to you.

As for judging the wind at 1000 yard match, most fire their 5 or 10 shots (depending on what club your at) as fast as possible before the conditions change and move one or two of your bullet string to another part of the target.

That's why it's much easier to take a spotter shot first when hunting, and then swing right back on the animal with a final, fatal shot before the conditions have a chance to change like they would if you were firing 10 shots at a target. One shot as compared to 10 does make a difference.

When you shoot fast during aa match, the chances of having a better aggregate for the year is improved.

Anyway, the original post I made was, you better know the wind conditions real good and most never know how to do it correctly, even the 1000 yard match shooters. that's why most of them fire their rounds as fast as they possibly can. Usually 25 to 30 seconds for 10 shots in a 1000 yard benchrest match

Later
DC

[ 11-26-2003: Message edited by: Darryl Cassel ]
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Old 11-26-2003, 10:08 PM
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Re: How accurate are angle cosine indicators?

Brent,

I tend to agree with Darryl here. Actually, He and I shot in a few relays together this year and several where his was a relay away from mine or that sort of thing. For the most part, we shot similar conditions, though sometimes one of us shot in horrible wind and the others relay was ok just later or vice versa. We shot on benches side by side and had extremely dissimmalar results and that's not uncommon there, especially at benches 1-5.

Just in the banquet shoot here in November, I shot the fourth relay. Relays 1 2 and 3 all shot 90's in absolutely dead calm conditions. Without a doubt, the best conditions of the year by a longshot. The fourth relay shot in what seemed to be excellent conditions also, but, all the scores dropped 10 points from bench 1 to 12. Here was a relay that over 1000 yards, I saw absolutely not one hint of condition and was blown farther off center than I had been all year (side to side). My score related to every other shooter in the relay and there were some excellent other shooters in the relays who shot great all year. Not a single one saw the change left in 4A and right in 4B. Not one. Now, all these shooters shoot at this range all the time and the flags showed absolutely nothing to any one of em.

We don't have flags over our game we hunt. And noone putting up spotters. Guessing the wind is something that people believe they can do only when they have shot thier entire life over easy conditions. Like, shooting where the wind is dead constant in 1 direction. If you show me a person who can read the wind at Cascade (Williamsport), well, I'd pay pretty good money to see that. The people who do well do just exactly what DC said AND they have guns that shoot well and they load well.

I know lots of people make great shots and I don't doubt that they can calculate a lot of the trajectory before pulling the trigger. But, all I can say is there is a lot more to reading conditions than what most people think. I know He'll tell ya that over the years a lot of people came to that range thinking they knew something about wind and could demonstrate that to the people there and left knowing they had a great deal yet to learn.

He's just saying that you have to be experienced with the terrain over which you shoot and even then sometimes you get stung. At the PA World open, we had a little wind and had hosts of people who couldn't keep 10 on. Shooters from our own club as well as from elsewhere. Even in the early morning relays, people had shots off.

I shoot at my house and I used to work out of my home. Every single day I would get my gun out for one and only one shot (at least) and shoot a steel target at some range (I have several) out my living room window off a bipod from the end table and couch. These would be anywhere from 300 yards 4" square to 600 yards 15" round. I prided myself on hits in ANY condition with a 22 cal every day. Make a good guess, dial, pow. Then I went to Cascade. Whooaaa!

I do not attempt to read wind any more. Period. My rule is, no adjustment over 8" under any circumstance. Period. That's all there is to it. There's just no guessin it here. Yes, people make an adjustment and guess right and win a relay and feel real proud of themselves. I've done that. But I'm not gonna try to BS you and tell you that I could do it again any other given day because anyone who knows the place would tell me correctly that I was full of excrement.

Now, to make a single shot on target at this kind of range... No deal. Perhaps elsewhere. Not here. I have yet to see a person show me otherwise. The terrain He hunts over where He lives is considerably steeper than this part of the state. I live on rolling hills, where 800ft is 2 miles from 1600ft of elevation. Wind is easy here. Pathetic. He's where 1500ft of change is 1/3mi. Wind has considerable verticle component AND it's swirling.

I know I'm gonna get a ton of argument on this, but, you know the saying, "I'm from Missouri, show me!" This isn't something anyone can come there to demonstrate. You'll just have to come here and try it out.
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Old 11-26-2003, 10:48 PM
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Re: How accurate are angle cosine indicators?

Folks,

The real question is how accurate is a cosine indicator out past 300 yards.

As for reading wind, I'll agree with you. You better understand wind if you want to shoot long distances, say over 400 yards. The only way to get good at is to practice, practice and practice even more.

Shooting angles is the same thing. Just because you have the wind figured out, doesn't mean you have the angle worked out.

Shooting a 35 degree angle at 600 yards is roughly a 540 yard shot using a cosine angle. The time of flight of the bullet will actually be longer than flat 540 yards shot.

So would you trust a cosine indicator for a shot like this?? That's the real question?

Happy Turkey everyone.
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Mathew 5:16

Distance is not an issue, but the wind will make it interesting!
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