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about ACI -Angle Cosaine Indicator-

SAS_Sniper

Sergeant
Full Member
Minuteman
May 16, 2009
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Italy
Can you tell me about this your opinions,and where can i find this on internet shops?

Thanks to all!
 
Re: about ACI -Angle Cosaine Indicator-

It's an expensive but popular piece of kit.

I don't have one. I use a Mildot Master with a piece of string to measure target angles, as recently shown on the <span style="font-style: italic">Advanced Sniper</span> episode of the <span style="font-style: italic">Modern Sniper</span> series on the Military Channel.

I only need one of those for all the rifles I own, and it will also do that math to calculate the change in dope required by an angled shot.

I like the guy who owns SniperTools, though, so I encourage you to throw money in his direction.
 
Re: about ACI -Angle Cosaine Indicator-

Badger ord sells them in a couple of flavors of mounts. Google to find all the other stores that sell them.
 
Re: about ACI -Angle Cosaine Indicator-

I don't know if Badger will ship them to you, as your location seems to be outside the US.

Does the RCS feed that T3 with AICS or AW mags?
 
Re: about ACI -Angle Cosaine Indicator-

Angle Slop Indicator ASLI from Horus vision at mountsplus (type ASLI + mountplus in your favorite search engine)

for me the best because you have the angle + the cosinus angle and the level bubble all together in one item.

you need your angle to know your angle :eek:) but to no the correction distance you also need to multiply the mesured distance by the cosin to get the corrected distance.

if you only have the angle you need to calculate the cosin and if you only have the cosin you don't have an idea of the angle if you don't do math.

in my knowledge ASLI is the only one to offer the 2 informations on one wheel.

you also need the bubble to correct your cant

the ASLI is sold around 100$ but you've got 3 items in it.

verry good quality product
 
Re: about ACI -Angle Cosaine Indicator-

Hider's, how do you like the ASLI, I know that you like the quality, but it looks a bit 'busy' to me. Have any problems with the tightness of it all?

Looks like a good alternative to the Badger one
 
Re: about ACI -Angle Cosaine Indicator-

I just looked at the ASLI, looks like it's $70 + shipping?
 
Re: about ACI -Angle Cosaine Indicator-

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">you need your angle to know your angle :eek:) but to no the correction distance you also need to multiply the mesured distance by the cosin to get the corrected distance.</div></div>

Calculating an angled shot by multiplying the actual distance by the cosine of the angle, and then using the dope for the modified distance, is called the Rifleman's Rule.

It doesn't work for significant angles at distance.

A better way is called the Improved Rifleman's Rule, which is to multiply the dope for the actual distance by the cosine of the angle.

For example, assume my dope for 1000 yards is 36 MOA, and the angle is 30 degrees.

The cosine of 30 degrees is 0.866. So, 36 * 0.866 = 31.18, so I'd use 31.25 MOA.

For the gory details, see:

Angled Fire Explained
 
Re: about ACI -Angle Cosaine Indicator-

Thanks Lindy, I was wondering about the differences between RR and IRR
 
Re: about ACI -Angle Cosaine Indicator-

...every fuckin' time, Lindy. I can't believe you just give this shit out for free. You are a damned genius.
 
Re: about ACI -Angle Cosaine Indicator-

Nah - I just learn from others.

If I have seen farther than others, it is because I was standing on the shoulders of giants.
-- Isaac Newton

In the sciences, we are now uniquely privileged to sit side by side with the giants on whose shoulders we stand.
-- Gerald Holton

If I have not seen as far as others, it is because giants were standing on my shoulders.
-- Hal Abelson

In computer science, we stand on each other's feet.
-- Brian K. Reid
 
Re: about ACI -Angle Cosaine Indicator-

This may seem like an idiotic question, but would mounting the unit to a 20MOA base would throw off the true angle, or can you zero the angle to "level," after the ASI is mounted?
 
Re: about ACI -Angle Cosaine Indicator-

You level the device.

But you don't need one. Angles are most important when they are extreme and at shorter ranges, like under 200 yards.

For example, how much vertical on target does a thirty degree angle create at 900 meters?
 
Re: about ACI -Angle Cosaine Indicator-

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: J-Ham</div><div class="ubbcode-body">...every fuckin' time, Lindy. I can't believe you just give this shit out for free. You are a damned genius. </div></div>

For Christ's sake, don't tell him that, it might go to his noggin.
laugh.gif


Lindy is full of info. Thanks man.
 
Re: about ACI -Angle Cosaine Indicator-

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Handloader</div><div class="ubbcode-body">Dope elevation for 780m and dope windage for 900m, thanks.
</div></div>OK. But keep going:

So a thirty degree angle equals about 4 feet at the target. You need to compensate for that. But thirty degrees at 900 is a very, very big angle.

Assume the same target at 900, but with a more realistic angle at those kinds of distances: ten degrees. That's still steep for that range. And it's a cosine of .98. Your dope at 900 is 9.2 Mils. Your dope adjusted for the angle is 9.1 Mils.

Now grab your ballistcs program and calculate the difference in drop: 328 inches (900m) minus 322 inches (882m) equals 6 inches. So, the difference on target between factoring-in the angle and not accounting for it is six inches.

Can you hold six inches at 900 meters? I can't.

Besides, misreading the wind by 1 mph will cause eight inches of bullet travel at that distance. What size is your target?

See where I'm going with this?!
 
Re: about ACI -Angle Cosaine Indicator-

Graham
I completely agree with your point for such small angles; however, I still pull out my Slope Dope and recalculate MOA. Great point.
 
Re: about ACI -Angle Cosaine Indicator-

A useful exercise is to use a ballistic program to run some numbers and see where the angle starts to make a difference.

I used JBM Ballistics, set up for a 175 Sierra Matchking at 2600 fps on an ICAO standard day.

The drops in inches on a 900 yard shot are as follows:

<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
Angle Drop(inches) Difference between 0 angle
0 429.9 0
5 429.4 0.5
10 424.5 5.4
15 417.7 12.2
20 406.4 23.5
</pre></div></div>

You can do this exercise with your load at various ranges.

The art of the precision rifle is based upon making distinctions between what matters and what doesn't matter in achieving the objective of hitting the target.
 
Re: about ACI -Angle Cosaine Indicator-

I am almost afraid to ask but if I know the cosine, why do I need the angle assuming I know the true distance to the target?
 
Re: about ACI -Angle Cosaine Indicator-

they can be hard to get shipped to outside the us, i live in ireland and had a hard time getting one , finally got them from here www.snipersystems.co.uk or google ''global rifle''. i emailed them and they rang me back to check with measurments between my scope and rail to make sure i got the right type of mount to suit. good service .