understanding drift and probability

[Harry's Lad]

Dave i always leave it on TRUE Mil calibration so i know that the MIL is always equal to the proper value, i dont like to mess with that and on my menace its at 10x. Mrad you can find it on some S&B scopes too written as 1click = 0.1Mrad and also on army field manuals. you dont have to convert to MOA if you are using a Mil retile and Mil turrets like me then no conversions need, if you hit 4Mils low you dial in 4Mils on the turret its a very common and efficient system. if i hit 1.5Mils left, i will simply Dial 1.5Mils of Windage, no conversions whatso ever thats the whole point about this. you're the first one i heard saying that they are not the same, if you look at the S&B manual it will explain how to use reticle and turret combo and each 1Mil on the reticle is divided into 10 increments on the turret for each 10 clicks represent 1Mil. 1Mil =10cm at 100m and thats what i use. the only time i use Imperial is for wind reading. i had MOA and Mildot reticle and even though it works, its old technology and when you have the facility of Mil/Mil just keep it that way. If you want MOA get a night force with MOA reticle.

So it looks like Mrad is simply an abbreviation of milliradians then. The Mil would seem to be an easily-calculated approximation to the milliradians (360/6400 instead of 360/6283.185; strange when 360/6300 would have been closer …). As far as I understand, the Mil was used for calculating artillery elevations in the days when such things were calculated on a slide-rule and with the use of tables. I simply converted Mils and milliradians to MoA to illustrate that, although they’re close in value, they’re not identical.

my scope is calibrated at 10x so people should check at what mag is theirs calibrated, something which many in my experience have no clue about. on the S&B i use on the 338 its First focal plain so any mag would do. i would actually include a note so that people check their mil-dot calibration, i often here many say i'm 1Mil left or 4Mils low and the shooter isn't even aware that his scope is not properly calibrated so his 1Mil correction is nothing in the real world.

I can see that the milliradians system has a lot going for it (compared to the more commonplace click/MoA systems). However, as you suggest, it becomes very important that the scope is correctly calibrated to the True Mil-Dot magnification – otherwise it all fails.

i don't know about the other pellets but the 31grain barracuda i have been buying are an excellent lot and i've been using the same data for as long as i have been buying them the last 3 years and no real variation.

Just shoot a couple of dozen through a pair of chronos, calculate the BC values, observe the variation and see if you still believe that!

here is a photo of the Mrad turret. each number on that turret represents a Mildot on the reticle so if you turn it to 4 then its like if you hold off 4Mils, the only difference is that you aim dead on.
http://accurateshooter.net/GOTW/zakscopex300.jpg

Looks like a nice piece of kit – just remember to keep it on calibration.

ATB
Dave