MRAD or MOA scopes? Target size matters.

A guide to MIL (MRAD) and MOA scopes.  Which one is right for me?

An understanding of optical adjustments is essential for the precision shooter.  Without a firm grasp on how they work, precision shooting can seem like wizardry.  New shooters looking to enter the precision rifle game often look for a greater understanding of optics, and most importantly, which system of adjustments and reticle to use.  Often they will seek information comparing MILS (MRAD) and MOA, asking which is better.  Here are my thoughts on which applications each system is best suited for.

Understanding MILS (MRAD) and MOA.

I’ve heard both described as “angles”, and while that is true, it is an oversimplification of each.  As boring as it may seem, to have the most basic understanding of either adjustment/reticle, you have to take a look at the basic geometry of a circle.

MOA stands for minute of an arc (sometimes in the shooting business, minute of the angle- which is technically incorrect) and is 1/60 of a degree.  Think back to elementary school, a circle has 360 degrees.  So if a circle has 360 degrees, and each degree has 60 minutes, an MOA is 1/21,600 of a circle (360 x 60 = 21,600).  As that space between two rays (the sides of an angle) increase from its vertex to a target 100 yards away, you would find this MOA covers (or subtends) 1.047″.  So, as shooters, we say something to the effect of 1 MOA equals 1.047″ at 100 yards, and then equals 2.094″ at 200 yards and so on.   MOA is an Imperial System of measurement, along with inches, feet, yards and pounds.

MIL is short of milliradian or MRAD.   A MIL/MRAD/milliradian is an angular measurement that is defined as .001 of a radian.  A radian is an angle within a circle where the arc length equals the radius.  Since a circle can contain 6,283 of these milliradians, a MRAD is 1/6,283 of a circle.  Since it is a unit from the metric system, some of the math is much simpler.  For instance, it subtends 10 cm at 100 meters, and 1 meter at 1,000 meter (1km).  Converting it over to imperial units, things get a little weird, 1 MRAD is 3.4377 MOA.  For purposes of this post, I’ll refer to MIL as MRAD, since this is “more correct”.

Often rifle scopes will have two different parts that use MRAD or MOA.  These are the wind and elevation adjustments, and in many modern precision rifle scopes, the reticle.  Typically the adjustments on most common scopes are either .1 Mil (or 1/10 of a milliradian) or 1/4 MOA.  At 100 yards, the .1 Mil adjustment subtends .36″ at 100 yards (about 1/3″) and the 1/4 MOA subtends .26″ at 100 yards (about a 1/4″).   From this we can say 1/4 MOA adjustments tend to be finer, or less coarse, than .1 Mil adjustments.

There are some notable exceptions to these common adjustments found on optics.  For instance, Nightforce Optics makes or has made scopes with 1 MOA, 1/8 MOA and .2 Mil adjustments.  To make things even more confusing, until recently, you’d often encounter MRAD reticles with MOA adjustments! Fortunately, shooters have grown wise to this folly and you don’t see them as much any more.

Let’s take a look at what this looks like at various ranges out to 1,000 yards.

The table above assumes the adjustments are in fact true MRAD or MOA values.  In practice, some optics may be slightly off either by design or accident.  While many shooters may not be able to make a wind call at distance with the finer adjustments shown, they will most likely be able to correctly call the elevation needed at a given distance.

So what is the advantage of a coarse adjustment over a fine one?

First, it is far quicker to dial fewer “clicks” on a scope.  When DARPA initially developed the XM3 Sniper Rifle, the first few guns had 1 MOA elevation adjustments (later changed to 1/4 MOA).  This allowed fairly rapid, albeit coarse, elevation changes.  Back in the day, I would run a Leupold Mark 4 with M3 1 MOA cams, it worked great on steel, but failed to provide the precise elevation adjustments I needed for smaller paper target matches.

Coarse adjustments tend to have allow more elevation in a given scope design, some of the 1/8 MOA scopes on the market lack an acceptable range of elevation adjustments for unknown distance shooting at long range.  Often the optic will be mounted on a canted mount tailored to the desired range.

Target size matters.

So what does this look like in downrange performance, it depends on how big your target is.

If you plan on shooting F-Class, you run into a similar problem.  Take a look at the NRA Rulebook, pages 37 and 38, and you’ll note the 10 ring on the 600 and 1,00 yards targets are less than 1 MOA, with the x ring less than .5 MOA.

Take away message- if you are shooting paper targets at known distances, MOA adjustable scopes are a better choice. If you are shooting steel, or have a military/law enforcement application, with larger targets, MRAD (Mil) adjustments are a better choice.

I shoot a lot and find uses for both MIL and MOA scopes.  As a case study, let’s look at same match, same shooter, same target, 3 different scopes.

For the past three years I’ve shot with a team at the New Jersey Marine Corps League’s Annual Carlos Hathcock Match.  Held on the last weekend in October for the past 22 years, its a blast to shoot.  The course of fire is pretty straight forward, a TQ-20 target is placed at 300 yards in the pits.  The shooter has 5 minutes of unlimited sighters during which time hits are marked, and a zero can be obtained.   After that, the shooter has 20 minutes to fire 20 rounds for score.  During the scoring phase, as the target is shot, the hole is pasted and score taken.  Unless the shooter has pretty high powder glass and keeps the gun on target, there is no indication of where the hit is.

Any rifle is allowed and it must be shot prone.  For front rests, a bipod that folds along side the rifle (they try to keep the gaming down) or sandbag without a defined shape is OK. You can use a rear bag, however, your hand must be between it and the rifle (I am unsure where this rule came from because Hathcock allowed rear bags at his school, however, it’s their tradition so it is fine by me).

Now I realize this match isn’t sanctioned by the NRA, and is only shot at one range, once a year, however it is a great lab for scope selection, so bear with me.

This is the target, a TQ-20.  Note the relative size of the 10 point box (chest) and 11 point box (head) and the Xring for each (circle).  Let’s see how each adjustment looks on the target…

Note the relatively small size of the head circle when compared to the actual distances each adjustment will move.  In this case, all other variables being equal, a finer adjustment will provide an advantage on a smaller target (for what its worth, my team’s won the 2 of the past 3 years with a mix of 1/8 MOA, 1/4 MOA, .1 MRAD and .2 MRAD optics- so maybe these things matter a little less than you think at times).

Take a look at the two rifles above, both have similar actions, A5 McMillan stocks and barrels chambered for similar 6.5 mm cartridges, the top rifle is equipped with a Nightforce B.E.A.S.T. with .2 MRAD elevation adjustments (.1 MRAD wind) while the bottom is equipped with the Nightforce Competition 15-55×52 scope and 1/8 MOA adjustments.  In this case, what you could do well with each rifle is determined by the optic.

MRAD or MOA, what do I recommend?  It depends.  But this is the guidance I would give based on what you are shooting at.

• If you shoot unknown-distance targets: get a MRAD scope, especially if your spotting scope has an MRAD reticle.
• If you shoot smaller targets and love the imperial system of measurement: get an MOA scope.
• If you shot MRAD in the military: stick with what you know!
• If you zero in your hunting rifle once a year and don’t make dial adjustments: stick with MOA, it is pretty easy to remember that on most scopes one “click” ~ 1/4″.

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