Interesting Outing With Mil-Dot Scope

[JoeMartin]

Had an interesting outing this morning with my Marlin 925 which has a Tasco 6-24x42 Target/Varment scope mounted on it.

I wa shooting from 100 yards off the bench in a variable 2 to 4 minute wind out of the SSW - which means it was coming at me from 10/11 o'clock across the muzzle. I wasn't using the best ammo in this wind - figuring I'd save my good stuff for a more calm day. I was using the Federal 510B ammo (1240 fps)...

Anyway, before my computer crashed (I'm on my wife's Lap Top right now), I had read that for a mil-dot scope to be most effective the power had to be set at '10' on this scope.

Having already been zeroed at 50 yards with this rifle using the Fed 510B, I set up a 'Dirty Bird' (shoot & See) target at 100 yards,,, made the elevation adjustment that I felt I would need, and began shooting.

My first 5 shots were 3 to 4 inches right but basically centered right of the ten ring. I gave myself 1 Mil-Dot (to the right) holding it on the green 'X' ring and low and behold I put 3 shots in the 'X' ring, 1 shot in the '10' ring at 12 O'clock, and 1 shot in the '10' ring at 9 O'clock... This group measured 1 3/8 inches.

Without my computer that crashed I can not recover where I read this information on setting your scope power to 10 (and of course your AO to 100 yards - if that's the range you're shooting from), but I would say that was good info for this Tasco 6-24x42 T/V Mil-Dot scope. As I recall, whoever wrote that info said that at 10 power, that is when your Mil-Dots kick in. They must have known what they were talking about.

I think I learned more in this outing about the wind effects and my Mil-Dot scope then what I've learned in the past 2+ years. I simply need to get more serious about this scope.

 

[hilbillee]

Re: Interesting Outing With Mil-Dot Scope

Joe,
A lot of mildot scopes have to be set on 10X for the use in ranging w/ mildots. Some such as Burris are 14X, and if I have read their manuals right NF are set to work on 22X. The 5.5-22 anyways. My Zeiss is set for 10X. All like these are 2nd focal plane. The scopes w/ 1st focal plane scopes will range at any setting. At my house the longest distance I have is 50 yds. Knowing that at 100 yds the distance between mildots is 3.6 inches I drew a grid on paper with the distance between the lines at 1.8 inches. I put the scope (Zeiss) & rifle on sand bags to keep them steady. Looking thru the scope I turned the power ring until the center to center of the mildots matched the 1.8 in. distance between the grid lines. When I checked the power setting on the scope it was set on 10X. I figure it's a simple way to check the setting on a scope when you don't have a long distance to do it in.

 

[JoeMartin]

Re: Interesting Outing With Mil-Dot Scope

Now that is interesting, checking out mil-dot at 50 yards. I will keep this in mind as that is a useful tool you came up with. I like it!

 

[villhelm]

Re: Interesting Outing With Mil-Dot Scope

my bushy is set for 12x you could say? but its also .5mil at 6x and 2mil at 24x so at 12x its 1mil which is why you could say "set" if you want it in 1 mil increments

 

[CColt45]

Re: Interesting Outing With Mil-Dot Scope

Joe,
The Tasco 6-24x42 target/varmint that I have is calibrated at 8 power according to their instruction sheet.

 

[targetterror]

Re: Interesting Outing With Mil-Dot Scope

Note that on many (most?) scope, the magnification dial is not calibrated perfectly, meaning that even though you set the dial for "10x", it may be some other magnification (eg 9.5x). On my Vortex Crossfire 6-24, the reticle is supposed to be a true mildot at 12x, but I measured it and the actual setting is slightly lower than that.

 

[TresMon]

Re: Interesting Outing With Mil-Dot Scope



Guys guys guys!

Kinda like HillBill said. -YOU- have to measure -your- individual scope to see at what power/zoom setting to where the mil dots read right. Two scopes same make/model can often need to be set at different powers to mil correctly.

The common way to check is to read 10 mils on a scale...

10 mils @ 100 yards should cover 36" on a tape measure or yardstick, except you can't see the little 1/16" lines through the scope at 100 yards.... oops.

So put your (metal 48" high quality from Lowe's/ Home Depot) "yard" stick @ 25 yards. (by the tape measure, not the range finder, the range finder can have you off 30" inches)

Get your rifle dead steady. Start adjusting the power ring on your scope until 10 mils perfectly measures 9", a PERFECT 9 inches on the scale while looking through the scope. Then mark/scribe/scratch a line across the scope tube & power ring so you will have lines to line up in the future. This is where your mil dots are reading right & are on size.

Have fun! Good stuff!

 

[pilotguy299]

Re: Interesting Outing With Mil-Dot Scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: villhelm</div><div class="ubbcode-body">my bushy is set for 12x you could say? but its also .5mil at 6x and 2mil at 24x so at 12x its 1mil which is why you could say "set" if you want it in 1 mil increments </div></div>

isn't it the other way around? with twice the magnification, the measurement between the dots should be halved:

http://www.snipercentral.com/bushnell4200.phtml
<span style="font-style: italic">
This is a second focal plane scope meaning the mildots will only be accurate at one power setting. In this case, that power is 12x and the power ring is marked in red at 12x, making it obvious at what power the mildots are accurate for. 12x is not a typical power to set the mildots to, but on this scope it is quite nice as it allows you to crank the scope up to 24x and then you can use the mildots with even more precision as each space between the dots will now represent .5 mils allowing you to get more precise with your mildot measuring. Also, on the other end, at 6x, they are again accurate with the distance between each dot now representing 2 mils. 12x was probably the ideal power at which to set the reticle to be accurate at and it is nice to see a larger scope maker take the time to think about it. </span>

 

[Lindy]

Re: Interesting Outing With Mil-Dot Scope

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">isn't it the other way around? with twice the magnification, the measurement between the dots should be halved</div></div>

One way to remember that is that as you turn the magnification down, each unit on an SFP reticle covers more of the field of view.

So, if you turn the scope down to half power, each unit covers twice as much. If a mil reticle is correct at 12 power, if you turn it down to 6 power, each mil now covers 2 mils.

TresMon said, <div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">So put your (metal 48" high quality from Lowe's/ Home Depot) "yard" stick @ 25 yards.</div></div>

25 yards is too close - and on many scopes, the parallax/focus won't work at 25 yards.

A good way to read the ruler at 100 yards is to put 1" orange Shoot'N'C dots on the ruler at the increments you want. They can easily be read to a quarter inch at that distance.

Here's the procedure I use:

I put 3 dots vertically so that the <span style="font-style: italic">center</span> of the dots are precisely 36 inches apart on an 8 foot piece of lumber at 100 yards. As TresMon said, measure that distance with a long tape measure - a laser rangerfinder is not accurate enough.

In other words, the center of the bottom dot is exactly 36 inches from the center of the middle dot, and the center of the top dot is exactly 36 inches from the center of the middle dot.

When the scope is on the correct power for a mil reticle to be accurate, 10 mils will exactly span one of the 36 inch gaps.

When the scope is turned down to exactly half of that power, then 10 mils will span the center of the top and bottom dots.

Make sure the mil marks are exactly in the center of the dot, not the top and bottom.

Mark the power ring at the half power mark - and, if necessary - the actual full-power mark, which may <span style="font-style: italic">not</span> be where the manufacturer marked it.

 

[TOP PREDATOR]

Re: Interesting Outing With Mil-Dot Scope

for those that don't know, Lindy is the math guru of the hide, take his advice as gospel.

i was kinda hoping he would chime in, for the best info on mildots, ballistics, etc. - he da man, check out his previous posts on the subject those subjects.

 

[TresMon]

Re: Interesting Outing With Mil-Dot Scope

<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">

TresMon said,

So put your (metal 48" high quality from Lowe's/ Home Depot) "yard" stick @ 25 yards.</div></div>

25 yards is too close - and on many scopes, the parallax/focus won't work at 25 yards.

A good way to read the ruler at 100 yards is to put 1" orange Shoot'N'C dots on the ruler at the increments you want. They can easily be read to a quarter inch at that distance.

</div></div>

Other than if the scope wont focus problem, Isn't reading a 1/16" scale @ 25 yards as accurate/ the same as reading 1/4" @ 100yds? (except my way I can reconcile the 1/16" line printed on the tape with no need for dots.)

Just curious if your way is better, or just different??? As always plz educate me.
(If the scope in question will focus @ <25yds. )

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TOP PREDATOR</div><div class="ubbcode-body">for those that don't know, Lindy is the math guru of the hide, take his advice as gospel.

i was kinda hoping he would chime in, for the best info on mildots, ballistics, etc. - he da man, check out his previous posts on the subject those subjects. </div></div>

Yeah what T.Pred said guys- Lindy is a gracious & absolute resource for us here on the Hide. When Lindy speaks, take notes!

 

[RTH1800]

Re: Interesting Outing With Mil-Dot Scope

Top Pred,
Lindy is not the math guru of the site. He is the overall guru of the site, as far as technical information goes. Nice to see him posting again.

 

[Lindy]

Re: Interesting Outing With Mil-Dot Scope

I use 100 yards, because when I check a scope, my priority is checking the accuracy of the elevation system, rather than checking the reticle. That's because most of the scopes we deal with are FFP scopes, so the accuracy of the reticle is a secondary factor - you rarely find one which has much if any error.

And it's easier to check the adjustments at 100 yards.

Since most scopes won't focus at 25 yards, I use 100 for everything.

If you have a scope which will focus at 25 yards, be very careful about the measurement. You must measure from the target to the objective lens of the scope very accurately. Use a tape measure, very carefully.

 

[TresMon]

Re: Interesting Outing With Mil-Dot Scope


Big thanks!