Rifle Scopes Who uses a "Angle Cosine Indicator"

[BMG50CAL]

Who uses a "Angle Cosine Indicator" for shooting

 

[427Cobra]

Re: Who uses a "Angle Cosine Indicator"

I use a Mildot Master, it does the math for you.

 

[Graham]

Re: Who uses a "Angle Cosine Indicator"

I don't like doing any more math in the field than I have to. If you want one, use an angle indicator instead.

 

[Woodlanddude]

Re: Who uses a "Angle Cosine Indicator"

I like it for a quick solution. Its only speedy if you can do the math in your head on the run though(works for me, but I'm an engineer-YMMV). Even better if you have a spotter helping get your firing solution. Hes got the range, you give him the angle he gives you solution.

 

[RONIN45230]

Re: Who uses a "Angle Cosine Indicator"

if you go that route, i'd get one that reads out in "cosine", not "degrees/angle"..... that eliminates a step in the correction process/math.

 

[Strangedays]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BMG50CAL</div><div class="ubbcode-body">Who uses a "Angle Cosine Indicator" for shooting </div></div>
I use one and like them. It works good paired up with Exbal.

 

[Graham]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RoninP80</div><div class="ubbcode-body">if you go that route, i'd get one that reads out in "cosine", not "degrees/angle"..... that eliminates a step in the correction process/math.</div></div>How?

 

[RemingtonSPS]

Re: Who uses a "Angle Cosine Indicator"

I use one. It does work great with Exbal. What I like about it is that out to about 600yds you can multiply the yards by the cosine and it gives you a quick and dirty angle compensation. I.e. target is lazed at 600yds, cosine reads .97, multiply 600x.97=582yds. Dial and shoot for 582yds. It is not the correct formula but I have found it to work at competitions effectivly out to about 600yds.

 

[jaxx1671]

Re: Who uses a "Angle Cosine Indicator"

MILDOT Master is the way to go. Unless you just have all the time in the world and want to work up math problems. the MM is so so so fast. Best 29.95 the US Govt ever spent on me.

 

[pshell]

Re: Who uses a "Angle Cosine Indicator"

I have used one, but found that I didn't need it. I actually went to a "High Angle Shooting Course" but ended up just running our normal dope. We never saw more than 96 on the indicator. It became a step that was just not needed to make hits on half size E-types and another useless piece of kit to account for. Great course though. I have not used the mil-dot master for this and doubt that I ever would. I would just aim at the crotch. Under extreme circumstances and with lots of time to get off that perfect shot, it will do the job and is not easily misplaced as it's attached to your rifle and starring you in the face.

 

[vman]

Re: Who uses a "Angle Cosine Indicator"

Yeh why not il invest in one for the future

+1 on mildot master ! awesome

 

[jaxx1671]

Re: Who uses a "Angle Cosine Indicator"

PSHELL,

Where did you go to a High Angle Course? USMC? Aiming balls is the standard for quick engagements at distance but will not always be reliable and accurate. Slight and rolling angles dont really matter, but it something that has to be calculated if you want to make the shot in certain environments.

 

[RONIN45230]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RoninP80</div><div class="ubbcode-body">if you go that route, i'd get one that reads out in "cosine", not "degrees/angle"..... that eliminates a step in the correction process/math.</div></div>How? </div></div>

check it out........

http://accurateshooter.wordpress.com/2008/05/07/angle-cosine-indicator-aids-hunters/

 

[pshell]

Re: Who uses a "Angle Cosine Indicator"

Thunder Ranch, Oregon, instructors were Rifles Only guys(Jacob and Frank)

Agreed that method is not all that accurate but it works, its quick and I just don't see having the time to get off a good shot using a indicator or mil-dot master. I'm not talking about shooting at steel, but at stuff that moves. I would rather have a good follow through, spot my impact and be able to fire again than worry about multiplying my dope by the cosine, etc..

Practice is going to teach you more about where your round will go than any scale or indicator.

 

[azimutha]

Re: Who uses a "Angle Cosine Indicator"

An important item to note if you are going to use the cosine, is you need to multiply it times either the bullet drop or your come-up for the range in question, not the range itself. In other words, for a 1000-yard shot at a 45 deg. angle, if you multiplied 1000 * .707 and used your hold for that you would be sorely disappointed.

For example, I have a round that has a come-up at 700 yards of 5.2 mils and at 1000 yards of 9.6 mils. If I multiply 9.6 * .707 I'll come much closer to what the value should be. Even then, it will just be close. That value, 6.8 mils, will still be .2 mils higher than if I'm shooting uphill and .4 mils higher than if I was shooting downhill at that range. That translates to a 7.2" difference uphill and a 14.4" difference downhill.

The third comment on the accurateshooter post referenced above has more info on this. And if you really want details, read Ch. 4 of Litz' Applied Ballistics.

 

[Graham]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RoninP80</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RoninP80</div><div class="ubbcode-body">if you go that route, i'd get one that reads out in "cosine", not "degrees/angle"..... that eliminates a step in the correction process/math.</div></div>How?</div></div>check it out........
http://accurateshooter.wordpress.com/2008/05/07/angle-cosine-indicator-aids-hunters/</div></div>Not exactly: With Exbal you input the angle, not the cosine. That, and it's better to use the improved rifleman's rule: multiply the dope, not the range to target.

What I meant was how does using a cosine indicator make the math easier by eliminating a step (compared to using an angle indicator)?

 

[TimResin]

Re: Who uses a "Angle Cosine Indicator"

Whats so hard about using a calculator? Cosine is opposite over hypotnuse. Image a right triangle and you are the top tip of the triangle. The opposite is the actual distance to the target and the hypotnuse is the distance the laser actually goes. All you need is a scientific calculator, the angle and the range. Multiply the angle by cos and then by the distance. The Formula is Cos(x)=x(range you want to find)/Distance from range finder. Example Cos30=x/700 Cos30= radical 3/2 * 700 = 606yd true ballistic range.

 

[Lowlight]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TimResin</div><div class="ubbcode-body">Whats so hard about using a calculator? Cosine is opposite over hypotnuse. Image a right triangle and you are the top tip of the triangle. The opposite is the actual distance to the target and the hypotnuse is the distance the laser actually goes. All you need is a scientific calculator, the angle and the range. Multiply the angle by cos and then by the distance. The Formula is Cos(x)=x(range you want to find)/Distance from range finder. Example Cos30=x/700 Cos30= radical 3/2 * 700 = 606yd true ballistic range.</div></div>

YA RG, what is so hard about using calculator... see !

 

[TimResin]

Re: Who uses a "Angle Cosine Indicator"

Ok I will simplify it even more. Here is the calculation on a Ti-83 calculator. Hit the Cos button then type the angle hit enter. And then multiply by the distance you got from your scope or range finder.

The only problem I have with using a Mildot Master is the sizes don't go small enough and its a little to rough calculation for me.

 

[Lindy]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The only problem I have with using a Mildot Master is the sizes don't go small enough and its a little to rough calculation for me.</div></div>

You're probably using only the left side of the MDM.

Use the right side of the MDM, which has mil dimensions down to 0.3 mils and target dimensions down to 1.75 inches. Use the scale which says "BULLET DROP" for the target dimensions.

And as Graham and others noted above, multiply the dope for the actual range to the target by the cosine of the angle. At significant angles and distances, it more accurate, and just as easy to do.

If you want to understand why it's more accurate, see:

Angled Fire Explained

 

[Chiller]

Re: Who uses a "Angle Cosine Indicator"

tag

 

[i_Adam_i18]

Re: Who uses a "Angle Cosine Indicator"

Top if the page ---> Topic options ---> Add topic to your watched topics. Keeps threads cleaner that way, not many people know about it though.

 

[TimResin]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The only problem I have with using a Mildot Master is the sizes don't go small enough and its a little to rough calculation for me.</div></div>

You're probably using only the left side of the MDM.

Use the right side of the MDM, which has mil dimensions down to 0.3 mils and target dimensions down to 1.75 inches. Use the scale which says "BULLET DROP" for the target dimensions.

And as Graham and others noted above, multiply the dope for the actual range to the target by the cosine of the angle. At significant angles and distances, it more accurate, and just as easy to do.

If you want to understand why it's more accurate, see:

Angled Fire Explained


</div></div>

Its off by a half a mil that way. What I am stuck on cause I not very good with vector math is what if it is a angle of elevation all we have been talking about it angle of depression? Cause the MDM doesn't compensate for angle of elevation only depression.

 

[WyoRanchHand]

Re: Who uses a "Angle Cosine Indicator"

Hypotnwhat?

 

[TimResin]

Re: Who uses a "Angle Cosine Indicator"

Hypotenuse the long side of the triangle if the triangle is not an Isosceles.

 

[WyoRanchHand]

Re: Who uses a "Angle Cosine Indicator"

Yes, I know. It was a joke.

 

[Jasmck]

Re: Who uses a "Angle Cosine Indicator"

I want a Hippopotomus for Christmas?

 

[Graham]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TimResin</div><div class="ubbcode-body">Whats so hard about using a calculator? Cosine is opposite over hypotnuse. Image a right triangle and you are the top tip of the triangle. The opposite is the actual distance to the target and the hypotnuse is the distance the laser actually goes. All you need is a scientific calculator, the angle and the range. Multiply the angle by cos and then by the distance. The Formula is Cos(x)=x(range you want to find)/Distance from range finder. Example Cos30=x/700 Cos30= radical 3/2 * 700 = 606yd true ballistic range.</div></div>YA RG, what is so hard about using calculator... see !</div></div> Apparently.

 

[Wild_Bill]

Re: Who uses a "Angle Cosine Indicator"

i use them for long range shooting. like shooting rabbits past 600 yards if you just multiplied the cosighn angle by the distance you would be out in elevation. they are best used with a ballistics program. One thing that does not get used in the equasion by multiplying the cosighn angle is that the projectile actualy travels the full distance not just the distance effected by gravity so at longer distances the projectile will still slow because of the air drag for the given distance. say we are shooting at 1000 yards but the cosign is 90 then the rough estamate would be 900 yards drop but the extra 100 yards the projectile actualy travels will slow the velocity so you would then have to work out a 900 yard shot with a retained velocity that would have occoured at 1000 yards see clear as mud.

Get one if shooting past 600 yards and you want the best chance of hitting but i also have a laser range finder and kestral 4500 weather station and a ballistics program. so when i shoot at a living animal at long range i know that i have had the practice and best equiptment to humanely put it down on the ground.

 

[strick9]

Re: Who uses a "Angle Cosine Indicator"

Very good read, btw if someone has one and is looking to dump it, pm me.

 

[TimResin]

Re: Who uses a "Angle Cosine Indicator"

Does anyone know if the Iphone/Ipod Touch Ballistics Program calculates for this?

 

[LoneWolfUSMC]

Re: Who uses a "Angle Cosine Indicator"

Ballistic FTE does.

 

[azimutha]

Re: Who uses a "Angle Cosine Indicator"

Additionally, Ballistic allows you to either enter the angle manually or you can aim it towards the target and it will use the iPhone/Touch's sensors to auto-enter the angle from the line of sight.

 

[AXEMAN]

Re: Who uses a "Angle Cosine Indicator"

i kinda like this one for the price...

http://www.mwgco.com/ar-15_accessories/product/HV-ASLI.html

bonus, it has a level too

 

[strick9]

Re: Who uses a "Angle Cosine Indicator"

anyone got a pic of that with the side rail mount?

 

[Wild_Bill]

Re: Who uses a "Angle Cosine Indicator"

i have one with the rail mount the mount is no where as strong as the badger units and i would not want to use it in military conditions but for my long range varmint firle it works well. i do have one issue with them though they only show the taper on your rail as 0 not 20moa the ACI allows you to get a true zero with the bore paralell to the aci. I have both the ACI with a US optics level is on my 338 and the Horris is on my 6mmBR.

I will try to get a pic for you.

 

[utnapishtim]

Re: Who uses a "Angle Cosine Indicator"

I've been considering one of these, but . . . I've got an EGW 20 MOA base . . . so I don't want to attach it to the base or the scope because that'll mess with the math. . . Where am I gonna put it?

 

[Lowlight]

Re: Who uses a "Angle Cosine Indicator"

Mess with the math, that is a new one...

 

[DaveV]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Mess with the math, that is a new one... </div></div>

Hey Frank, which end of my gun do I mount my Coriolis Correction Meter?

 

[TOP PREDATOR]

Re: Who uses a "Angle Cosine Indicator"

my chart gets a little funky when i copy and paste, but there it is. range the target, get your degree of angle, multiply your actual yardage by the cosine value = your "adjusted yardage"

adjust sights for the adjusted yardage. not much math, just 1 multiplication problem. ACTUAL YARDS X COSINE=YARDAGE WITH ANGLE


DEGREE OF ANGLE / COSINE VALUE CHART

ANGLE> 0 1-8 9 10 11 12 13 14 15 16 17 18
COSINE> 1 .99 .98 98 .98 .97 .97 .97 .96 .96 .95 .95

ANGLE> 19 20 21 22 23 24 25 26 27 28 29 30
COSINE> .95 .94 .93 .93 .92 .91 .9 .89 .89 .89 .87 .86

ANGLE> 31 32 33 34 35 36 37 38 39 40 41 42
COSINE> .86 .84 .84 .82 .82 .80 .80 .78 .78 .78 .75 .74

ANGLE> 43 44 45 46 47 48 49 50 51 52.5 55
COSINE> .73 .72 .70 .69 .68 .67 .65 .64 .605 .605 .57

ANGLE> 57.5 60 62.5 65 67.5 70 72.5 75
COSINE> .53 .5 .46 .42 .38 .34 .30 .26

ANGLE> 77.5 80 90
COSINE> .215 .17 0

ACTUAL YARDS X COSINE=YARDAGE WITH ANGLE

how do you get angle? old school, use a half moon protractor and string with a weight on it, a silva compass to give you degrees, a RV (camper) level gauge.

new school, buy the tool.

 

[utnapishtim]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DaveV</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Mess with the math, that is a new one... </div></div>

Hey Frank, which end of my gun do I mount my Coriolis Correction Meter? </div></div>

I'm guessing by the HardeeHarHars that the 20 MOA base won't affect the reading on the ACI?

Should I simply apologize for my ignorance, or should I go find a forum that's a bit more forgiving for the amateurs just getting started in the sport?

I'll try the apology first.

Please forgive.

 

[Lindy]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">just 1 multiplication problem. ACTUAL YARDS X COSINE=YARDAGE WITH ANGLE </div></div>

The problem with doing that is that it's not accurate at significant distances and/or angles.

More accurate is to take the <span style="font-weight: bold">dope</span> for the actual distance through the air, and multiply <span style="font-style: italic"><span style="font-weight: bold">that</span></span> by the cosine of the angle.

Still just one multiplication, and more precise - and you can do it with a Mildot Master.

To find out why, read:

Angled Fire Explained

 

[Fighthard]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Mess with the math, that is a new one... </div></div>

Yeah, can't you just set your zero stop to 1,000 meters and just aim for the cranial vault? I mean even if you are off a little bit you are still gonna make a solid hit with any caliber, except .22 Short. You would have to hold over about one of the dots...

BTW, LL what is the best scope for my CMP 40X?

 

[michaelt454]

Re: Who uses a "Angle Cosine Indicator"

I forgive you, but then again I'm newer and probably even dumber than you when it comes to all of these formulae and calculations, so take it for what its worth.

 

[azimutha]

Re: Who uses a "Angle Cosine Indicator"

Yep, as Lindy said (and I mentioned above): You've either got to multiply your drop or your come-up to get the adjustment (and it will be very close then to what you can get with a ballistics program).

 

[MudBug]

Re: Who uses a "Angle Cosine Indicator"

So if your adjustment is 9 moa and your cosine is 0.9 then you do 9x0.9 and get 8.1 moa?

Is that correct?

 

[Lindy]

Re: Who uses a "Angle Cosine Indicator"

Egggsactly.

 

[chip8541]

Re: Who uses a "Angle Cosine Indicator"

You still have to measure angle. The string hanging from a Mildot Master is less than ideal compared to an ACI. Use them together.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 427Cobra</div><div class="ubbcode-body">I use a Mildot Master, it does the math for you.</div></div>

 

[chip8541]

Re: Who uses a "Angle Cosine Indicator"

No offense but you would be wrong. I highly doubt you would have qualed with normal dope.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pshell</div><div class="ubbcode-body">I have used one, but found that I didn't need it. I actually went to a "High Angle Shooting Course" but ended up just running our normal dope. We never saw more than 96 on the indicator. It became a step that was just not needed to make hits on half size E-types and another useless piece of kit to account for. Great course though. I have not used the mil-dot master for this and doubt that I ever would. I would just aim at the crotch. Under extreme circumstances and with lots of time to get off that perfect shot, it will do the job and is not easily misplaced as it's attached to your rifle and starring you in the face. </div></div>

 

[Lindy]

Re: Who uses a "Angle Cosine Indicator"

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The string hanging from a Mildot Master is less than ideal compared to an ACI.</div></div>

I'm afraid that turns out not to be the case.

The string hanging from the Mildot Master not only can be read to a resolution of one degree, which is not the case with the ACI, but it has a longer baseline than the ACI as well.

In addition, there is no question that the plumbline on the MDM is vertical, which may or may not be the case with the ACI, depending on how accurately it was installed. You don't have to point your rifle at something to measure the angle to it, so your spotter could be doing that while you're setting up, or you could do it yourself without having to expose the rifle.

A single Mildot Master serves for every rifle I own, in addition to being much less expensive, and I'm going to carry it anyway for it's calculation abilities as well as for computing the distance to UKD targets.

I have no objection, though, to people spending money for an ACI. I like Ward Brien, the inventor. The country is in the midst of a recession, so spend away to stimulate the economy.

Just don't buy one on the belief that you're getting more for your money than you would by buying a Mildot Master. You're getting less.