Rangefinding without electronics – Vortex Solo R/T 8X36

vortex solo r/t rangefinding


Knowing the distance to an object can be very handy, whether it’s to make an accurate shot with a rifle or just as recon. There are multiple ways to do it and they all have their pros and cons, but what if you want a system that will always be there no matter if it’s SHTF and there are no batteries or if there is an EMP strike and all electronics are out. Then it would be a good idea to learn how to range with milliradians. The most common way they are known or seen is a mil-dot scope. I think we have all seen the mil-dot reticle, but do you know how to use one properly? I didn’t know until recently, and I still don’t know all of the uses, but I have learned basic rangefinding using Mils. I have never owned a mil-dot scope, but I will be looking for one in the future.

mildot scope

A standard mil-dot reticle


I’ve been looking at Vortex optics pretty hard lately, wanting to upgrade from my compact Bushnell binoculars, when I ran across the Solo R/T 8×36 monocular.  I decided on purchasing one after fondling it several times at a local sporting goods store, being on sale sealed the deal. Comparing it to the cheaper, yet higher magnification Solo 10×25, the R/T’s image is brighter and sharper with better eye relief. At the time I was curious about the manual range finding abilities of the R/T but didn’t know how to use it, so that wasn’t a critical consideration.  Vortex Solo R/T 8x36

The slim design and the ease of use steered my decision more than anything. Being a monocular it’s much easier to carry in a pocket than similarly sized binoculars, plus it also has a sturdy belt clip attached that makes it easy to clip onto your gear. It features focus knobs for the reticle and the image. I find once set I rarely have to touch either. The only design feature I don’t like is a lack of lens caps. Vortex states that their Defender line O-40 and E-10 will fit, and they do with a simple modification. The only other problem I have is the carry case is almost useless, but I think it will be easy enough to find a molle pouch that will do the job.


mrad reticle Vortex Solo R/T 8x36

After spending a good part of a day learning about Mils and manual range finding I decided to try this in the wild. The main drawback to manual ranging is knowing the size of your target, but there are ways around this by measuring objects with known sizes. I ranged several “targets” around town and quickly became pretty comfortable with the method. It’s daunting at first but really breaks down to be fairly simple. Using a formula to range in yards, along with a cheat sheet, and the quick range silhouettes kept it quick and easy. The formula for yards is: (Target size in inches X 27.77 / Target size in Mils = Yards to Target) It is easy enough to change the formula out for whichever unit you want.

(Target size in inches X 27.77 / Target size in Mils = Yards to Target) It is easy enough to change the formula out for whichever unit you want.

Solo R/T ranging truck 1

I started simple with this truck. I figured an 18″ rim, which measured 5 mils.

18″ X 27.77 / 5 mils = 100 Yards

Range guy 333yd

This guy fit just inside the 300m quick range silhouette and measured out at 6 mils tall. I calculated him at 72″.

72″ X 27.77 / 6 mils   = 333 yards


These first two tests were simple. The truck was fairly close and the 8x magnification made it easy to measure the rim. The man in the field was also ideal as he fit almost perfectly in the 300m silhouette and was standing upright making him easy to measure. The next few proved to be more of a challenge. The following tests had mixed results, but having some practice and studying the reticle substension chart above, I feel confident that I could range more accurately now. I used GPS/Aerial Maps (ie. Bing Maps) as an alternate method to verify the ranges later to check my accuracy.

Ranging guy at 277yds

This guy was slightly more challenging as he was sitting down. He was just larger than the 300m silhouette. I tried to measure his torso to head at 4 mils figuring on 40″.

40″ X 27.77 / 4 mils = 278 yards

Later I verified his distance using Bing maps and was within 1 yard.


This next one was the most difficult, and partly because I chose a poor target and didn’t have experience measuring fractions of a mil. If I could have gone prone or steadied the optic better and also knew what parts of the reticle measured 0.5 mils I know I could have ranged it more precisely. However, a small target is still difficult to range accurately at longer distances and any error in measuring can result in huge errors in range.

Ranging a truck with Vortex Solo R/T

I couldn’t find a known size in the area besides the 15″ rim on this old Chevy truck.

The best I could tell at the time was that it measured at 0.75 mils.

15″ X 27.77 / 0.75 mils = 555 yards

Figured at 0.5 mils comes out to 833 yards, quite the difference.

Verified later on Bing maps it was actually 723 yards which would have made the rim 0.576 mils, which is pretty hard to measure.


Not being satisfied with the measurement on the truck rim at that distance I looked for another target. This area is usually pretty busy with people walking around, but no luck for me on that day. I decided to measure a door on a house a little further back from the truck, as doors have a standard height of 80″.

measuring a door to find range with a solo R/T

I found a good angle to a door beyond the truck. A standard sized door is 80″ and I measured it at 3 mils.

80″ X 27.77 / 3 mils = 740 yards

Verified later on Bing maps it was actually 776 yards, only a 36 yard difference, which I think is pretty good for that distance.

Overall I was really satisfied with my ranging ability using the Solo R/T, especially for being my first time out. More magnification would make it easier to measure targets, but without some kind of tripod or mount to keep it steady it wouldn’t help all that much. If I had taken the time to go prone and really tried to get a steady shot I think I could have ranged these more accurately. These were all done from sitting in my truck with it running.

Despite the drawbacks of manual ranging, it is still way closer than guessing. I use the T.L.A.R. (That Looks About Right) method on a lot of things, but I’m not very good at guessing beyond about 200 yards, and below that range doesn’t matter too much. Even using a laser rangefinder on some of those shots might not have been perfect. Most of them are only 4X magnification and with foliage or other obstacles in the path can create errors.  The best way is to use multiple methods to determine range.

For more information on all of this, see the videos below:

Tags: , , , , , ,

Leave a Reply

Be the First to Comment!

Notify of
Follow by Email



%d bloggers like this: