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.

So 1/4 MOA would be a finer adjustment than 0.1mrad on a scope? (Assuming 0.1mrad clicks. Never used one)

Originally Posted by Pushover

So 1/4 MOA would be a finer adjustment than 0.1mrad on a scope? (Assuming 0.1mrad clicks. Never used one)

Greetings Pushover
Yes slightly. 1/4 MoA works out to a little over 7.3mm at 100 m and 0.1 mrad is 10 mm.. I think that there are some scopes are 0.05 mrad. I just checked the units used on the Hornady metric drop charts are actually mrads and not mil as stated. After working almost entirely in metric for over 45 years I find going back to UK units a real pain so work in metric as much as possible.
Regards Grandpamac.

good point, I just checked my applied ballistics app. only MIL option, no Mrad...

Originally Posted by grandpamac

Greetings Pushover
Yes slightly. 1/4 MoA works out to a little over 7.3mm at 100 m and 0.1 mrad is 10 mm.. I think that there are some scopes are 0.05 mrad. I just checked the units used on the Hornady metric drop charts are actually mrads and not mil as stated. After working almost entirely in metric for over 45 years I find going back to UK units a real pain so work in metric as much as possible.
Regards Grandpamac.

yes, thanks for that. I work in metric in everything except shooting/loading hahaha

I doubt you would you even notice the 2. 8 mm difference between units that's 1/8 inch in old money.
One of my scopes adjusts in half moa clicks and that's never been an issue. What spins my wheels is mil dot reticles with moa adjustments.
Might not be useful but these are the approx angles in military mils (6400 to the circle) the fact that there are 6283 milliradians in a circle adding a few on makes no practical difference it's less than 2% and makes the math easier.

Originally Posted by Marty Henry

I doubt you would you even notice the 2. 8 mm difference between units that's 1/8 inch in old money.
One of my scopes adjusts in half moa clicks and that's never been an issue. What spins my wheels is mil dot reticles with moa adjustments.

Greetings Marty Henry,
Yes, not a union made in heaven. All three of my mil dot scopes are thus afflicted. I tend to use the knobs to zero for the load and ignore them thereafter. I seem to have quite a range of click values from 1 MoA 2.5 power Lyman, 2/3 MoA 8 power Lyman, a 6 power Pecar that could be 1/2 MoA or possibly 1 cm at 100m and others as well. Even a few friction adjusted ones. Keeps you on your toes as some are not marked.
Regards Grandpamac.

I would expect most scopes to be basically 10mm per click at a 100m , you can always check it on a scaled post/tgt at 100m , Nato mils is just a rounded off version of actual , Russians use there own version I think its more actual.

Here's some basic seat of your pants converts from Metrick to Imprill.....
Or this link for exactness if your a profectionanal..... The further you shoot the more this matters. Extreme Spread matters most though I've found? when you get a new scope. Sight it in so it hits exactly where the crosshairs are placed. Then wind up 8clicks shoot , wind up another 8clicks shoot and then measure your results. Wind down 4clicks measure wind down 8clicks and measure. You should get even spaces between shot placings and now you should have custom click measurements to use with that ammunition.... I find this to be a real world solution for the rifle I'm sighting in.... I only worry about the Bloody wind>>>>
https://metricunitconversion.globefe...sion_table.asp

1/4 inch =6mm 1 click @ 100yrds 91.44meters
1/2 inch =13mm
1 inch = 25mm
4 inches = 100mm

Originally Posted by 35whelen

Here's some basic seat of your pants converts from Metrick to Imprill.....
Or this link for exactness if your a profectionanal..... The further you shoot the more this matters. Extreme Spread matters most though I've found? when you get a new scope. Sight it in so it hits exactly where the crosshairs are placed. Then wind up 8clicks shoot , wind up another 8clicks shoot and then measure your results. Wind down 4clicks measure wind down 8clicks and measure. You should get even spaces between shot placings and now you should have custom click measurements to use with that ammunition.... I find this to be a real world solution for the rifle I'm sighting in.... I only worry about the Bloody wind>>>>
https://metricunitconversion.globefe...sion_table.asp

1/4 inch =6mm 1 click @ 100yrds 91.44meters
1/2 inch =13mm
1 inch = 25mm
4 inches = 100mm

Greetings 35whelen,
I got a thorough grounding in UK to metric units in the mid 1970's. I was working as an architectural draughtsman and we were forever converting from feet, inches and fractions of an inch into metres and millimetres. We had a very useful table that helped with this. Affordable pocket calculators were still somewhere in the future. I was still needing to do the conversions from pre 1975 plans right up until I retired in 2015. Worth remembering is that 1 inch is exactly 25.4mm although at one time the UK inch was slightly shorter and the US inch slightly longer. Survey plans were in chains and links which we had to convert into metres, at least this was simpler than feet inches and fractions. Almost all US units were different to the UK ones, just another trap.
Regards Grandpamac.

Originally Posted by grandpamac

Greetings 35whelen,
I got a thorough grounding in UK to metric units in the mid 1970's. I was working as an architectural draughtsman and we were forever converting from feet, inches and fractions of an inch into metres and millimetres. We had a very useful table that helped with this. Affordable pocket calculators were still somewhere in the future. I was still needing to do the conversions from pre 1975 plans right up until I retired in 2015. Worth remembering is that 1 inch is exactly 25.4mm although at one time the UK inch was slightly shorter and the US inch slightly longer. Survey plans were in chains and links which we had to convert into metres, at least this was simpler than feet inches and fractions. Almost all US units were different to the UK ones, just another trap.
Regards Grandpamac.

Thats a bit of a blast from the past

As a schoolboy I remember being a chainman for my godfather, surveying out the new Wellington dump location: having to hold the spring balance to keep the chain at a predetermined tension. I wonder if surveyors these days get shown all this sort of gear, that is really only one-two generations old

Originally Posted by XR500

Thats a bit of a blast from the past

As a schoolboy I remember being a chainman for my godfather, surveying out the new Wellington dump location: having to hold the spring balance to keep the chain at a predetermined tension. I wonder if surveyors these days get shown all this sort of gear, that is really only one-two generations old

Greetings XR500,
Talk about blast from the past. My first job, other than mowing lawns, was a two week stint as a chainman's assistant for the May school holidays about 1964. My father had wangled it for me. The work was plotting the centre line for part of the Napier Hastings Expressway. The surveyors had been through and put in some set out points and we were working between them putting in pegs every chain or so. Wet days were spent making pegs out of the totara beams from the old Mohaka Bridge from the Napier Taupo Road. These were split from sections of beam and then shaped with a very sharp tomahawk. And we think that recycling is something new.
Regards Grandpamac.

Memories. I still have a 10 chain steel chain with links etc lyi g about somwhere from forest service days. The fabric tapes were useless so we lugged around the steel chains and drums, abney levels a d slope correction tables.

Always something to learn eh