Thread: Mils and mrads

Greetings All,
With more scopes having "mil" based reticles and adjustments I thought a few notes on Mils and mrads and the difference between them. The radian unit has been in use in mathematics has been in use for around 600 years although only given the name in the late 1800's. Its use in gunnery was realised early. 1 milliradian (mrad) works out to 1m at 1000m. There was however a problem. There are roughly 6,283.2 mrads to a full circle which gave gun layers fits so a round number, often 6,400, was used. The US turned up late to WW1 and with hardly any equipment. Some may have noticed that the steel helmets worn by US troops look just like the Brit ones which is because they were. Also there weren't enough Springfield rifles and no useable machine guns or artillery. French and other field guns were used which had mil based bearings. After the war the US adopted the mil (two different versions for a while) which later became standard for NATO.
All very interesting you say but WTF does this have to do with scopes. The mrad is ideal for scope adjustments as 0.1 mrad is exactly 10mm at 100 metres. 0.1 mil is about 9.8mm at 100 metres. Unfortunately our US cousins are a mite careless with units and use the two units interchangeably. The Leupold background data states that their mil type reticles and adjustments are in mrad and many are so marked. I suspect other manufacturers may be the same.
I saw an add for one of the new Bushnell scopes the other day in which they proudly stated that their clicks are exactly 0.1mil. I do hope they actually meant 0.1 mrad which would be much more useful.
Regards Grandpamac.