Rather than disuading a shooter by telling them they need to invest in, what for most is, the most expensive part of their rig, we just promote the fact that an mrad scope is equivilant to a 1/3 moa scope! Do we tell 1/4 moa guys to go and change their scope?When shooting seriously on a minute derived target I would still tell shooters to infinitely prefer MOA scopes. Try coaching a serious team where 1/2 the shooters use mRad scopes and the other half use MOA scopes. And how about two coaches trying to coordinate their coaching !
BUT I did learn something. I never realized just how close the click conversion is to 1/3 minute for a 1/10 mRad scope. But I digress. I want to defend the use of Radians as angle measure in the appropriate place. They are not some obscure thing because someone wanted to be different. In many circumstances they are an absolute necessity.
Humanity cannot choose the physical world in which we live. We have to fall in with the Physical restraints around us if we wish to understand and master our environment and progress. Straight lines are a part of life. BUT so are Circles - especially when we live on a Spherical World. (OK - not perfectly Spherical but very very close).
There have been attempts to pretend to change the Physical World to suite us. For example, the infamous Indiana Pi Bill.
Worth reading about it just for laughs.
https://en.wikipedia.org/wiki/Indiana_Pi_BillWe cannot change the fact that when we cut worm wheels and matching Worms we MUST introduce the natural Physical Constant Pi. When we move around the curved Earth's surface instead of move in a straight line we MUST introduce Pi in the calculations.
There are other natural Physical Constants. They keep surfacing in Mathematics. Another hugely important one is Eulers Constant
'e'. And others. 'e' (2.718281828459........) like Pi, can never be exactly expressed as a decimal number. Nothing sneaky about that. Nor can 1/3 or 1/7 for example. Blame the fact that Humans have 10 fingers as much as anything else and seem to think that 10 is a magic number. Don't get me wrong - Decimalization of values is a great concept but it is not a fundamental thing in our natural world. Just a man conceived convenience. But Pi and e go further because neither can be exactly expressed as a fraction. I will not detail the origin of 'e' . People can research that if inclined.
A consistent system is needed for Mathematics and Calculations. Pi and e MUST be introduced to keep it consistent - no amount of ignorance such as the Indiana Pi Bill can override that. It flows out inevitably into calculating many basic things.
Whenever we calculate the effects of spin of a projectile we MUST introduce Pi. Rotational velocity, Rotational acceleration, Rotational momentum and Rotational energy calculations are part of a consistent system ONLY when Pi is involved. All essential in Ballistics. The results of calculations all come out in Radians or Radians/sec etc. It is convenient to then convert to more common units such as Degrees or Rotations or Rotations per sec because that is what people relate to. Just as on Historical Rifle Ranges and Targets, people relate more to MOA.
Computer calculations are all the time converting from some commonly used rotational measure into Radians then back again. It is a MUST. There are probably more stuffups in Engineering computer programs than anything else because the conversion to and from Radians is forgotten. It even flows over to entry of angle values in hand held calculators and spread sheets.
The fact that the mRad became common in Artillery Plotting is because the value of an angle in Radians is conveniently close to the Sine of its Value for
small angles. For large angles this fails and proponents had to pretend that the value of mRads is somehow sacred. Hence approximations for the full circle in mRads have been redefined as the NATO, or Swedish or Japanese or Russian value. Again the Indiana Pi Bill comes to mind.
https://en.wikipedia.org/wiki/Milliradian gives good information.
I do think it is worth gently insisting that a mRad be called by its right name. It is the first step in understanding what a mRad really is. A Radian as approximately 57 degrees (180/Pi) and the 'm' means 1/1000 of that. Just as in m Metre, m Amp, m Volt, m Sec. The word Mil is a lazy meaningless concept as a measure used by itself. And Mrad is also wrong. That means one million radians !!!!
Sorry to be pedantic. But sometimes there are places when these concepts do matter.
Peter Smith.