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Holding over compared to dialing in MOA

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Unread 02-04-2004, 08:15 PM
Platinum Member
Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: Holding over compared to dialing in MOA

You're right! Ohhhh it's a beautifull +30 deg F calm day out there today, boy I'm kickin myself I'm not out there right now!

The satisfaction of a 1 shot, 1 kill is what does it for me. I've really got no interest in sighter shots before taking game, it just does nothing for me, personally. I'd loose the vast majority of opportunities if I relied upon it too, that's another main reason I don't use it.

Sighter shots are very rarely able to be seen in the terrain I hunt in, so it's pretty much a waste to count on it and not learn to place shots precisely with the first shot. The first shot method takes practice, and lots of it too, the sighter shot don't require much if you can see hits and know you're within the accuracy limitations of your rig. Some knowledge of ballistics is required with the sighter method, or you might be firing MANY shots to get POI near POA.

Preparing with real world drills makes one faster and faster, without doing so you'll never ever be prepared. Training pays the big dividends needed to be successful. The more you train, the more certain things simply become second nature, like riding a bike. Every aspect must become pure habit, freeing valuable time to focus on last second variables affecting the shot and the decision process itself on whether to take it, or not, and why.

I still have room to break a shot four times faster than I can right now, and with even more confidence, but more traning is simply needed to rise to that level of performance. Up to 1 minute in bad circumstances to range, calculate, take last second observations and considerations into account then break a shot, instead of 15 seconds or less, to me, leaves a lot of room for improvement in my book, but that's about where I'm at right now. [img]images/icons/smile.gif[/img]
Brent Moffitt
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Unread 02-04-2004, 08:41 PM
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Join Date: Jan 2003
Location: The rifle range, or archery range or behind the computer in Alaska
Posts: 3,830
Re: Holding over compared to dialing in MOA

All I do to get perfect dial accuracy is instead of calculating clicks based on .25 I use .26175 If you want to shoot 1k and your bullet drops 250" just divide 250/2.6175 That WILL be the exact number of clicks you need for the shot.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.
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Unread 02-04-2004, 10:48 PM
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Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: Holding over compared to dialing in MOA


Right on Brotha! [img]images/icons/smile.gif[/img]

Pretty simple what I'm looking for tho.
1 minus the cosine for each angle gives the correction factor to replace each corrosponding cosine number with.

Here's a list - Replace cosine with bold type correction number.

Angle - Correction factor - Cosine

5 - .004 - .996
10 - .015 - .985
15 - .034 - .966
20 - .060 - .940
25 - .094 - .906
30 - .134 - .866
35 - .181 - .819
40 - .234 - .766
45 - .293 - .707
50 - .357 - .643
55 - .426 - .574
60 - .500 - .500
65 - .577 - .423
70 - .658 - .342
75 - .741 - .259
80 - .826 - .174
85 - .913 - .087

We talked about this before, but I can't remember the details of the design. A couple alternatives to consider that "may" or "may not" be possible, as well as increasing the versatility of the unit.

The weight you use in the drum, if it could be relocated 180 deg in the drum by the user, you could print the Correction factor numbers on one half, and the Cosine numbers on the other half and simply reverse change the weight location to be able to use either set of numbers on the left side of the scope.

If you can't change the weight location for some reason, printing both sets of numbers as described, you could still install the ACI on the right side of the scope and rotate and rezero the cover 180 degrees. One set of numbers would have to be printed inverted so to speak if you did it this way though.

Maybe the drum can be installed backward on the spindle, in which case one set of numbers would be inverted and could work on either side, with either set of numbers facing you. With the weight on bottom, both sets of numbers on each side would need to face up correctly, that's what I mean by inverted is all... printed opposite of each other on the paper or label on the drum.

What are the possibilities of reversing the drum on the spindle, and the labeling of both sides?

My wife don't let me have girlfriends. [img]images/icons/wink.gif[/img]
Guns are fine, girls are a flat, NO GO! [img]images/icons/grin.gif[/img]

Personally, I hate dealing in clicks unless it's dark out. I multiply my MOA by 4 if I really need the click number.

The click formula there is simplified at 1000 yards, but and requires the extra math step at any other range, as just moving the decimal don't work anymore.

1100 yards for example -

((250"/11.00)/1.047)*4 = (250"/11.00)/.26175. So you save a step here, "if" you're after click values.
Brent Moffitt
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Unread 02-05-2004, 12:18 AM
Posts: n/a
Re: Holding over compared to dialing in MOA

Brent: let me start off by saying, “Holly Cow”… that’s quite a dissertation! As far as an ACI depicted that way, I am not planning on it. Those that aided me with prototyping it all agreed on having the “Cosine” numbers indicated as the standard methodology. I went off on angles due to a requested special order. I am not planning on making any more that way because the user is locked into using just the angles. With the Cosine’s, you have a redundant system that you can either use to multiply to your distance to target or count up for the angles (should you want them).

I have wanted to take the step and purchase a Night Force with the NP R2 reticle in it for quite awhile now. The “Quality” is there and so is the reputation; perhaps it is time. I believe that the NP R2 reticle with Exbal’s Palm software would really work well.

[ 02-04-2004: Message edited by: W ]
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Unread 02-05-2004, 06:38 AM
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Join Date: Dec 2002
Location: Asuncion, Paraguay
Posts: 39
Re: Holding over compared to dialing in MOA

I think the easiest way is BMGMike's approach:

1- From a ballistic program find the drop D(horizontal range) at 100 yds. This number will not have much of a variation in the real world, so don't worry to find out the "real" one.
2- Measure your scope height H (axis of scope to center of bore), 0.1" accuracy is fine.
3- Zero at 100 yds, horizontal range. When you are done, the angle between the line of sight and the bore line is veeery close to:
A = (D + H)/1.047
D and H in inches; angle A in MOA
As Brent stated this value is usually close to 4.0 MOA
4- Find out your come ups with a ballistic program, and validate them on a horizontal range. Now you have your confirmed come ups from the 100 yds baseline zero in MOA.
5- Add the angle A to your come ups (in MOA). Now you know the angle between sight line and bore line at any range, we'll call these values "scope elevation". Forget about drop, come ups, etc., just think in "scope elevation" from now on.
6- For angled shots, just use W's level (or any other device).
The formula is:
corrected "scope elevation" = "scope elevation"*cos angle

SIMPLE and FAST [img]images/icons/grin.gif[/img] [img]images/icons/grin.gif[/img]

Edited to add: to avoid confusion, when zeroing at 100 yds you may put the elevation turret "0" at: 100 yds zero setting - A (for example, back off 4.0 MOA).
This way the scope reads directly "scope elevation": when your scope is at "0" the erector is parallel to the bore, when it is at "A" setting it is zeroed at 100 yds, etc.

[ 02-05-2004: Message edited by: TiroFijo ]
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Unread 02-05-2004, 08:09 AM
Platinum Member
Join Date: May 2001
Location: Pennsylvania
Posts: 1,757
Re: Holding over compared to dialing in MOA

It also depends on the distance you are hunting/shooting and the equipment you use.

Some on this forum hunt one way and others hunt another. The equipment used is entirely different.

If the shots are only in the 500, 600 or 700 yard range, the one shot method will work fine most everytime. With our big guns and the setup we have, those shots at that range, are taken directly at the animal unless there's a real "stong" cross wind to deal with.
We then revert to the sighter shot method to make "sure" of the shot. It all depends on what is encountered as far as conditions.
A nice calm day at 6 or 700 yards is a one shot kill for us to.

Once the range goes beyond 1000 yards though, it's a different ballgame entirely.
That's why we rely on the sighter method.

I think the range and conditions dictates the style and method one "should" employ here.

To be "sure" of the bullet impact and placement and at the distance we shoot, the sighter method works for us to perfection because of the range we set up for and have been successful at.

To each his own on style, method and equipment owned.

You still need a good rangefinder and an accurate drop chart to begin with. Optics (bigeyes) are most important along with a good hunting partner or team member also.
DC [img]images/icons/smile.gif[/img]
Darryl Cassel
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Unread 02-05-2004, 08:55 AM
Bronze Member
Join Date: Dec 2002
Location: Asuncion, Paraguay
Posts: 39
Re: Holding over compared to dialing in MOA

DC, there are so many environmental factors that are difficult to predict/estimate past 800-1000 yds that the sighter shot (if available) is the wise thing to do.
Who can estimate with precision the complex wind flow over terrain, the wind speed within 1 mph, or an accurate correction for a varying wind (in speed and direction)?
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