Rifle Scopes ACI Question Update

B

Brownbear

Sergeant
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Minuteman
Jan 31, 2007
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Winterville, NC
#1
I'm interested in getting an ACI and I want know what experiences you have had with the angle consine indicators. Is it accurate? What are some of your opinions about it? Thanks.

<span style="font-style: italic"><span style="font-weight: bold">Updated on 5/4/07</span></span>

<span style="font-style: italic"><span style="font-weight: bold">Does anyone have opinions about the Badger Ordnance high and low mounts for the angle consine indicators? What version has work best? What I heard is that the low mount is the newest version. Marty made the high version and later the guys in the military wanted something lower because it was interfering with the focus and the turrets on the scopes. </span></span>
smile.gif
 
#4
Re: ***Angle Consine Indicator***

I use a piece of string attached to a Mildot Master, with a ballpoint pen for a weight. It reads the angle out to one degree.

Once I know the angle, I take my elevation data for the actual range to the target, and use the Mildot Master to multiply that by the cosine of the angle.

That's more accurate than multiplying the range by the cosine of the angle.

For a reference as to why, see:
http://www.exteriorballistics.com/ebexplained/article1.html

I'm going to carry a Mildot Master anyway, so it costs me nothing to use that method, except for the string.

There's no CDI factor, though - except for girls who like guys who spend their money on them rather than gear.
 
#6
Re: ***Angle Consine Indicator***

The feed back you seek has been given. They flat out work. Nothing more can be said about a good product.

I however am also interested in the Horus, I would be more interested if it were aluminum instead of acrylic.

Cheers, Doc
 
#11
Re: ***Angle Consine Indicator***

Raf,

I think Horus is the sole supplier. Looking at the pic above I wonder if the USO level would fit in the ACI screw hole ...............

Maybe there needs to be a meeting of the minds between "W", "JWBIII" and "Marty from Badger"

Cheers, Doc
 
#12
Re: ***Angle Consine Indicator***

Yeah, it's plastic.
Still, how many of us still use wood stocks.

It would be interesting to do a hammer test on the two.
laugh.gif


It would be nice to have both AC and degrees in the same unit.
The level is a nice addition.
The fact that it mounts on the scope means it would be protected somewhat in a fall by the illumination/windage protrusion as in Kirk's pic above.

That looks like an SN-3 like mine.
 
#13
Re: ***Angle Consine Indicator***

It doesn't look like the Horus can be zero'ed like the ACI can.
Still, do we with 20-30MOA bases need to worry about 1/3 to 1/2 a degree? Can we really read any of these tool to that degree of accuracy?
 
#15
Re: ***Angle Consine Indicator***

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rafael</div><div class="ubbcode-body">It doesn't look like the Horus can be zero'ed like the ACI can.
Still, do we with 20-30MOA bases need to worry about 1/3 to 1/2 a degree? Can we really read any of these tool to that degree of accuracy? </div></div>
Since the ASLI is mounted to the scope, the amount of tilt built into the base has no effect. Of course you could have a fair amount of elevation dialed into the scope, but like you said: why worry about a fraction of a degree...
 
#18
Re: ***Angle Consine Indicator***

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rafael</div><div class="ubbcode-body">Yes....too little to worry about.
laugh.gif
</div></div>

20 Minutes is .33 degrees.
 
#19
Re: ***Angle Consine Indicator***

javentre;
Thats why I said 1/3 to 1/2, as many are using 20MOA but 25's and 30's seem to show up now and then.
laugh.gif


Nodark;
Who cares about lefty's?

Actually, I write with the left but do everything else with the right. I am all mixed up.
 
#22
Re: ***Angle Consine Indicator***

Badger sells the cosine mount by itself...no reason why you couldnt use it on the Horus. The one made by Sniper tools (Did I get that right?) can be mounted on a ring just like the Horus in the pics...BO just made a nifty mount to clean up things.

DCC
 
#23
Re: ***Angle Consine Indicator***

Well, it looks like a bunch of you guys had some ideas on different ACIs. I appreciate you all given insight on a great product. Do any of you guys have a preference on the high or low mount by Badger Ordnance. I noticed on Badger Ordnance, Marty has two differents mounts. I have seen pictures of the two different mounts. It looks like the low mount sits too far down. And also the high mount might get into your way of the turrets on the scope. Any ideas or opinions? Thanks.
 
#27
Re: ***Angle Consine Indicator***

Concur with the rail mount and if/when I buy another it'll be the down one as I think it will drop it right in line with the bore and stay out of the way of the knobs.

Cheers, Doc
 
#32
Re: ***Angle Consine Indicator***

Guys i didnt have a time to get into this the last time i posted but here are a few pieces of info that i would like to share.

Ward the guy that came up with the ACI use to sell his products for quite along time to HV. Not sure what happened between HV and www.snipertools.com but he decided he would not distribute his product thru HV anymore. At that time i guess things went to shit. Now if you compare the two products it seems that the HV is a COPY of the orginal and is made of PLASTIC!!! The HV does have the bubble level in it that the snipertools ACI doesnt.

As for bubble levels to me they are old news as well. As you guys know bubble levels are crued way to measure level. I have been using the Level Grouse from www.alamofourstar.com. The level grouse is 10 times more precise then a bubble level. You can get the level grouse set to .2 degrees left/right off center. That alot better then a bubble level. Also with a bubble level you have to take your eye off your reticle/target to check your level as soon as you move back to the target/reticle you can be back off. The level grouse you can see while you look in your scope.

It is imperative that the ACI be zeroed to the bore of the barrel, not to the scope.

The user of the HV ACI will never get an accurate or correct read because with the numbers on the wheel, behind the index mark, it is impossible to get a "head on" read. The index mark must sit next to the number and be as close as possible to that number without compromising its internal clearances.

2) Drop some acetone on the HV ACI, and watch it haze up and weld shut. This will not happen with snipertools ACI. The Machined Cast Acrylic that is used for the lenses, which also has a special treatment done to it, resists Acetone! If you spilled Acetone on the lens, you could wipe it off without any damage to it. Just don't let it soak into it.

Either way i highly recommend the sniper tools ACI over the HV any day!!

 
#34
Re: ***Angle Consine Indicator***

Guys, W came out with first unit. Period dot. He sold them when he was teamed with Horus. Then he left Horus and they started selling a version of thier own. Do the math.

I usually use my Mildot Master but on a couple of my weapons I have the Sniper Tools/W made version. Its the original and the one I use.

 
#35
Re: ***Angle Consine Indicator***

Nomad;
I have the ACI currently.

It works.
Still, I can come up with a few counters to some of what you said. I am not picking a fight with you, but I feel my points are worth considering.

The HV can be read from behind the scope at extreme angles, where the ACI needs the user to be on the same level as the ACI(looking towards the horizon) to read it well.

Also, why would anyone be using Acetone on either of them?

I understand that one can zero the ACI and not the HV.
I don't see where its that important. Lindy and others use the Mil-master with a string and I bet he is not within even 1 degree on average. Even a corrective base of 20MOA is only 1/3 of a degree of error.

Also, I would really like to have degrees instead of AC markings to simplify my dope sheets. Most of my Ballistics software uses degrees, and I can use the Mil-Master in event of failure.... with the same dope sheets.

Just a few thoughts.
 
#36
Re: ***Angle Consine Indicator***

Almost forgot.
Unless you are actually sighting down the bore or the barrels exterior, having the ACI zero'ed to the bore may not be of benefit.

How do most people use them? Are they looking thru the scope or along the barrel?

 
#37
Re: ***Angle Consine Indicator***

Rafael: If you look at the readings on the ACI, you will note that the closest together the angles are is about 2.6 degrees, and they go up from there.

The Mildot Master is marked in 1 degree increments. Can I line it up with the target accurate to one degree? Probably not. On the other hand, one probably cannot align the ACI with the bore to an accuracy of one degree, either.

And in practice, neither makes much difference. Going from a 25 to a 28 degree angle at 1000 yards makes a POI difference of about 1 MOA according to my ballistic program, and the odds of having a shot that long at that kind of angle is not very great.

When splitting hairs, it helps to have a good idea of the size of the hairs.
laugh.gif


It does matter, at significant ranges and angles, how you calculate the elevation once you have the angle. The Improved Riflesman's Rule is greatly superior to just multiplying the actual range by the cosine of the angle, as noted in the following article:

http://www.exteriorballistics.com/ebexplained/article1.html



 
#39
Re: ***Angle Consine Indicator***

Raf- no sweat bro i know you are not starting a fight, i like good conversation and as we all know there are many ways to skin a cat and get to the same result.

What might be good for one might not be good for another.

As you stated you like to know the angle. I rather have my cosine and multiply it and be done.

As for looking at it i can see my ACI with little effort so once again it doesnt really mess me up.

I used Acetone as a chemical that is used around rifles from time to time, we all know alot of solvents we use and cleaners are much harsher as well.

To me being plastic is bad juju!! One good bump and that piece of plastic could be gone. In the cold it will be much more prone to breaking. I just like the how solid the ACI. Its rugged and durable.

I figure if i am going to buy a piece of gear i want the strongest most durable out the box. Why have to replace often.

As in everything in shooting consistancy is accuracy!! We spend alot of time zeroing are rifles and trying to make perfect bullets, why shouldnt you have you do all you can to make it the best it can be.

 
#40
Re: ***Angle Consine Indicator***

Ward;
Its's nice to hear from the gent who made the gear.
Thank you too, for supplying a nice piece of gear.
Glad to do business with you.

As to the Acetone danger, I have yet to clean my lenses this way but undersatand the value. I do believe the danger is fairly slight...that one would get Acetone on it. The only procedure I have seen includes a q-tip soaked in the chemical and rubbed on the lens.

As to math and science, this discussion has not yet clarified how one employs the ACI. Simply zeroing it to the bore does not mean its gets used properly. Short of removing the bolt and sighting the target thru the bore, it is easy to be off by a degree or more. With a 20MOA base and/or using the device by sighting the target thru the scope you can tighten the accuracy of the reading, depending on how much elevation you have dialed on at the moment of use. I need to dig out the instructions you supplied and refresh my memory on how to decide when the bore is on-target at the moment of the reading.

I will play with it over the weekend to see what kind of accuracy "I" am capable of in my readings.



 
#41
Re: ***Angle Consine Indicator***

Glad you replied to this, Lindy.
Understand I am not knocking Nomad, yourself, or even Ward with my observations. The possibility for error in reading is much of the motivation, beyond wanting to understand this stuff better.
I apprecaite the help from all of you.

To be honest, I have not yet used the Mil-master for these readings, yet, and forgot that it was marked down to single degrees.
laugh.gif


I like the idea of being able to use the ACI for readings, rather than dangling a string, and this was my motivation for my ACI purchase. Not knocking one method or the other.

As I said in my reply to Ward, there is the possibility of read error with the ACI. When its comes down to it, the MM and string method does seem an accurate method. No offense intended towards anyone, but it actually gives a surface to sight along. What do you do in a high-wind situation?
laugh.gif


Yes, the IRR makes alot of sense to my simple mind.
"And in practice, neither makes much difference. Going from a 25 to a 28 degree angle at 1000 yards makes a POI difference of about 1 MOA according to my ballistic program, and the odds of having a shot that long at that kind of angle is not very great."
Okay, I will try to be a little less uptight about my reading error.
laugh.gif
 
#42
Re: ***Angle Consine Indicator***

Tiro;
In my case, I actually inserted a 308 indicator rod in the muzzle and set up the rifle to allow me to get the bore perfectly level using a machinists level on the rod. Then I zero'ed the ACI.

I doubt the average user would go this far.
laugh.gif


Still, when I arrived at my first ever match and employed the ACI, I took the AC reading by putting my x-hairs on the target and looking at the ACI. I paid no attention to the amount of dope I currently had dialed on the scope. Does anyone dial to thier 100yd zero, or better yet...a point where the x-hairs have been proven to be aimed at a point down a line that is perfectly parallel to the bore?
laugh.gif
 
#43
Re: ***Angle Consine Indicator***

Rafael: if you want to get a parallel-bore zero for that purpose, it's pretty easy.

First, measure the height of the center of your optic above the bore.

Second, adjust the scope until your point of impact is exactly that measurement lower that the point of aim in the scope.

Notice, however, that we're talking about really small angles here. My .308 load took right at 38.25 MOA to get to 1000 yards this afternoon. That's an angle of less than two-thirds of a degree above the 100 yard zero.

Recall what I mentioned about the size of the hairs we are splitting - we're down into RCH range, I think. I'm not worrying about those kinds of angles given the range of effect I've already mentioned.

 
#44
Re: ***Angle Consine Indicator***

Nomad;
Glad you understand where I am coming from.
laugh.gif


Yes, the original intent I had was to have dope sheets with me that already had angled-fire adjustments on them. I "was" hoping to avoid doing math when I could just look up the data.
All of my current software uses degrees for this. When I orderd the ACI, I didn't even think about the fact that it was cosine readings. Stupid me.
laugh.gif
If I do things the way I intended I will just have to turn the output to cosine figures for my dope sheet.

I am still rather new to using these tools in the field, and my ignorance shows here.

I feel I it may appear like I am knocking Ward's product. That is not my intention. Still, the HV being plastic does not bother me. Plastiic has its place in many of the components of our weapons systems, including the ACI. Neat fact that it is coated to resist damage from Acetone. I didn't realize that.

I remain doubtful that everyone or anyone is employing the ACI or other rifle-mounted indicators to within less than a few degrees, but am open to any suggestions. I am actually leaning towards resetting my ACI zero to coincide with my scopes aimpoint somewhere between my 100yd zero and another point at the other end of my average-shot envelope. This should truly get me to within 1/3 of a degree in my aimpoint for the reading of the indicator.

It matters, it doesn't matter, it matters, it doesn't matter.
laugh.gif


Damn...I am a troublemaker.
laugh.gif






 
#45
Re: ***Angle Consine Indicator***

LOL
Yeah, Lindy....it's an RCH for sure.
laugh.gif

If you read my reply to Nomad, I may have hit on a method to get me to the center of where I will employ the ACI.

Thanks for humoring me here, I really apprecaite the input.
 
#46
Re: ***Angle Consine Indicator***

Raf,

You may have seen a card similar to this before.......somewhere.

SlopeDope.jpg


I know this guy, he has done all the math.........
laugh.gif


It actually seems to work pretty good on angles. Course it might be that I yanked a shot or two....
laugh.gif


Cheers, Doc
 
#47
Re: ***Angle Consine Indicator***

Yeah, Doc.
A good friend makes the same cards for me too.
laugh.gif


Are you going to stay in the area when you get out?
If not, I am screwed.
laugh.gif


BTW....sorry about the parking ticket the other night.
"Nah....they are not checking these spots this time of year!".
 
#48
Re: ***Angle Consine Indicator***

I just made some comparisons with a ballistic program, and shooting a typical 308 load a one degree error (from 30º to 29º) makes for a whopping 3.6" POI error at 1000 yds...

A more realistical situation, from 24º to 25º at 800 yds, the error is only 2".

I don't think I'll worry too much about about it
smile.gif
 
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