Using mildots to estimate distance - do people use a calculator?

[superlative]

I heard the formula for estimating distance = height of target x 1000 / size of target in mildots. So assuming a height of 2 yards of a person, it would be 2000 / size of man in mildots.

Now I am pretty quick with mental arithmetic, and I did engineering math in University, and I find that pretty hard to calculate in my head. Quick! What's 2000 / 1.75?

How do people use mildots to calculate distance in the field? Do they carry calculators with them?

 

[kombayotch]

When using the reticle, don't try and do the math on the fly, create a little reference chart that changes it from a math exercise into a look-up.



Careful you don't go past the limits of reticle ranging in your table. Use the distances where the danger space at each consecutive step no longer overlaps with caution... its a good idea to color code those cells or identify the limits in some way.

 

[667]

There's an app for that...

 

[Juster]

Mildot range estimation isn't particularly accurate. And at longer ranges you need to be accurate. So it doesn't matter much.

 

[Snapshot]

There is also the MilDot Master.

 

[kombayotch]

The thing with the little card is that you can put it in a wrist coach. Then you can range without breaking your shooting position, without even taking your cheek off of the stock.

Not as accurate as your laser rangefinder but much much faster in some situations.

 

[Gunnerlove]

The thing with the little card is that you can put it in a wrist coach. Then you can range without breaking your shooting position, without even taking your cheek off of the stock.

Not as accurate as your laser rangefinder but much much faster in some situations.

And required in some matches/serials, and a good skill to have in a world full of laser detection/location equipment.

 

[Alpheus]

Careful you don't go past the limits of reticle ranging in your table. Use the distances where the danger space at each consecutive step no longer overlaps with caution... its a good idea to color code those cells or identify the limits in some way.

Danger space? Overlaps with caution?

Speaking of hold-over "christmas tree" reticles... most scope manufacturers also offer them in moa-based versions. Are there any reasons beyond personal preference to go for the mil version instead?

 

[buster]

There are more choices in mil/mil scopes.scope manufactures seem to be gearing up for mil/mil and producing some moa/moa to satisfy those who want them.

 

[kombayotch]

Danger space? Overlaps with caution?

Speaking of hold-over "christmas tree" reticles... most scope manufacturers also offer them in moa-based versions. Are there any reasons beyond personal preference to go for the mil version instead?

There are quite a few mil vs. MOA threads on the forum, one right below. Have a look at those.

Danger space is the range of distance over which you will still hit your target while aiming at it's center even if your scope is not set to the correct distance. For example, lets say you were shooting a 175 SMK at 2650 fps. wanted to hit a 12" target that you thought was at 860 yards. If the target was actually at 870 yards, you would still hit the bottom edge of the target because the trajectory is 6" lower than it is at 860 yards. If the target was actually at 850 yards, you would hit the top edge of the target because the trajectory is 6" higher than it is at 860 yards. JBM will calculate this for you if you enter a target height and check the "Include Danger Space" box at the bottom left.

If you put the mil ranging formula into a table, you will notice that at some point the numbers start taking very big leaps. Look at the following table:



Notice the leap in range when you go into the red areas? At that point you have gone well beyond the capabilities of the reticle. The range you calculate is not reliable and relying on it will almost certainly result in a large miss. Even in the yellow and higher green boxed, a difference of 0.05 mil in your reticle measurement will give you a distance that is not within the danger space of the box above it or the one below it. But, it will likely still be close enough that you can correct the shot easily enough. It depends on the size of your target and the ballistics of your cartridge.

In matches, you are generally ranging the target you are going to shoot, so the limits of reticle ranging for those targets is smaller than it would be in a real application where the target is often larger than the object you are ranging (torso height, for example). Danger space is a useful tool for determining the limits of ranging with your reticle. When the danger space overlaps for consecutive cells, ranging with the reticle is pretty safe.

 

[kombayotch]

An illustration of danger space:

Bersaglio is the target. The target is 2y in height. In the example above, y would be 6" for a 12" target.

 

[Juster]

Golf rangefinders claim up to 90% accuracy, mildots work on the same triangulation principle. For the reasons given by kombayotch, this is pretty useless for range estimation at longer ranges. Mildots can be useful for wind hold offs.

 

[kombayotch]

Some considerations when ranging with the reticle:

-The larger the object you are ranging, the further you can range it accurately.
-The taller the target, the larger the ranging error can be tolerated (due to larger danger space)
-The flatter the trajectory of your cartrideg, the larger the ranging error you can tolerate (also due to larger danger space).

You must be mindful of perspective when ranging with the reticle.