This entry was posted on 01/12/2021.
By Chris Parkin
This is a common question when choosing riflescopes and when you really get down to it, both are quite simply just different units of measurement, the same as miles or kilometres, metres or yards, pounds or kilograms and pints or litres. Although not specifically metric or imperial versions, the MRAD system is considered to be a simple metric format simply because it all calculates in base ten and can be defined exactly with metres or centimetres perfectly. For example, 1 MRAD or milliradian spans 1 metre at 1000 metres. Think of it as a simple triangle and as you draw closer, that same milliradian is 10cm at 100 metres, a simple tenth of the size. Now, break that down into individual scope clicks, most commonly advertised as 1cm or 10mm at 100metres, and you realise each click is now exactly 0.1 MRAD or milliradians too. Neither way of explaining it is more or less accurate, both are identical within the physical manufacturing tolerances of the riflescope’s internal mechanisms themselves.
Now swap to minutes of angle (M.O.A.) and the general `rule of thumb` is that one inch at 100 yards is 1 M.O.A. yet this is not actually correct. That `Minute` actually subtends or spans/covers 1.047” at 100 yards and although that seems a minute discrepancy, because it’s all about angles and extending distances/triangles, this mistake is continually amplified becoming more critically incorrect. Now consider those 100 yards are based on 3 feet per yard, 12 inches per foot and you also inject less simple mathematics into any calculation. Some shooters consider the simple 1” at 100 yards to be known as `Shooters M.O.A.` whereas the correct 1.047” at 100 yards to be `Target or True M.O.A.` so another vague variable is injected.
When it comes to physical mechanical clicks within your scope for zeroing or correcting fall of shot for longer ranges, they are most commonly ¼ M.O.A. but sometimes described as ¼” clicks? There are options for ½ or 1/8th units which although not specifically more complex, further confuse some shooters. For example, on an airgun at close ranges of say 25 yards, rarely ever 100 yards, those clicks are worth a quarter of their value in terms of physical point of impact change on target. So for example an 1/8th true M.O.A. click at 25 yards actually equals ¼ (distance) x 1/8 (click value) x1.047” (M.O.A. at 100 yards) = 0.0327” (0.8mm). Can you or your rifle tell the difference from pellet hole to pellet hole at 25 yards of that much presuming no butterflies loiter nearby in terms of air movement? Quite probably not so in those circumstances, ¼ clicks (target or shooter’s M.O.A.) are a more helpful 0.0654” or 1.6mm (sorry to bring metric units in here but I think it simplifies visualisation). Now at 100 yards and further on rimfire or centrefire, this is less of an issue and if you always think in angular measurements rather than actual movement on target, life is less complex, but you might now think `why order an 1/8 click scope` for an airgun anyway and I would generally agree, it might sound more precise, it is, BUT is it more helpful?
When ranges extend and precision counts, finer click values are sometimes beneficial, especially for target shooters at extreme ranges. Those 1/8th clicks at 1000 yards are now 1/8×1.047”x10, so 1.3” bullet shift. A quarter click is 2.6” at which point you are about on the money for the world record five shot group sizes even possible from specific rifles (regardless of exact position on target) from 1000 yard benchrest shooters, never mind target shooters who MUST put the bullets in the centre for score values to count. Formal traditional “target rifle” or “F-Class” shooting still seems to like the Minute of angle for this reason so read on why…?
The 0.1MRAD/ click (10mm/1cm at 100 metres) so commonly seen on long range tactical optics would now equal a bullet’s positional change of 10cm at 1000 metres (approximately 1090 yards). Scale that back to 1000 yards, and each click theoretically moves your bullet by about 9.14mm/0.35”. I shall tabulate all this as it’s getting very complicated now, but this is all theoretical mathematics and has taken no account of the ammunition consistency, rifle consistency, the shooter, the wind, the atmospherics etc. etc.
To add a further factor, 5mm clicks are available (0.05 MRAD) on a few scopes, so you can halve or double all the 10mm click values as necessary, but all still works on base ten and almost as fine in terms of bullet positional movement as M.O.A. but here is the thing, manufacturers themselves often make vague mathematical statements of angular correction, often stating ¼ M.O.A. = 7mm at 100 metres. Neither technically fully agree…think out to long ranges again where small math errors amplify! A quarter inch is 6.35mm so multiply that by 1.09 for metres and it becomes 6.9mm, close, but not exactly. A 5mm click would be more precise at that distance but are rarely seen.
None of this actually matters that much in the real world as it’s far less of a factor than the other variables are to a shooter, but endless discussion over which is better often distracts from actually going shooting, learning your kit, experimenting safely and recording results, `DOPE` is Data On Previous Engagement after all! If you work in clicks, that’s great, you need to keep count though, if you work on the engraved turret markings, also great, but one or the other will suit different shooters and that’s before we bring first versus second focal plane into the equation, (1st being more logical, 2nd perhaps more precise in a nutshell). How physically large is your target, how often will you change distances in a competition and need to re-calculate? Fewer clicks and simple maths will always be a benefit if the targets are comparatively large and changing all day, FFP and Metric is my choice and that of many in this scenario, but for single distance shooters, 2FP and imperial/M.O.A. perhaps offers slightly more precise bullet placement and simpler reticle concentrating on just a precise central aimpoint. Nobody can decide for you and people are too keen to give you their personal opinion with no regard to your needs)
Finally, turrets can only physically fit so many clicks in a turn, each needs a tiny ball bearing under spring pressure to drop into an equally tiny groove machined somewhere within to make that tactile and repeatable detent click. If the threads controlling the erector tube to make that mechanical change are very fine, controlling equally minute angular shift within, there become an awful lot of `clicks` to count and fit in, the detents can become vague and the turret often descends into just a whir of smudgy clicks, not solid perceivable `clunks`. Easily overrun, easily miscounted and I can think of a few (naming no names) scopes, that have pathetically little mechanical range for the `long range` shooting they so enthusiastically advertise capability of!
Learn your system, neither is intrinsically better but each has slight benefits in certain areas which might suit you, but not necessarily the shooter next to you. For simple single distance zeroing of a sporting or hunting rifle rifle at a single distance, just don’t worry about it, but for multirange shooters, it’s worth looking into the specific balance of benefits and not just what a manufacturer advertises as “long range”. One fact I would underline though is this, DO not combine the two, wither on paper or with click values versus reticle subtensions (either FFP or 2FP), you are inviting demons into your brain for calculation ?
|Point of impact change per click|
|Click Value||100 Yards/Inches||100 Yards/mm||100 Metres/inches||100 Metres/mm|
- 1000 yard benchrest just needs bullets grouped on target, specifically where isn’t an issue
- Course 10mm@100m MRAD clicks can be beneficial when speed is involved
- Id ALWAYS advise reticles that match your click values regardless of units used
- More clicks and multiple rotations really benefit from more complex turrets
- Multi range shooting disciplines are growing in popularity and scopes are enabling this more easily
- Pure target disciplines still seem to attract MOA with finer clicks
- Simple quarter M.O.A. clicks are very common
- The centimetre click was most commonly seen on European hunting optics in the past
- There is no real best option, MRAD v MOA, just differences
- Ultimately, closer range air rifles dont really benefit from ultra fine clicks
- Very fine clicks can become overwhelming for multi distance courses of fire