struggling with moa

[TattooedGun]

Strictly speaking, the MOA is a part of one degree of the 360-degrees in a circle. Google it and you'll see the exact definition easily enough. Use of MOA was adopted by shooters and artillerymen amongst others as a way of easily setting or resetting sights / aim. The 1-inch at 100 yards and equivalent for longer distances isn't too far out and is fine for short distance use. In actual fact, the exact amount is 1.047" per 100 yards, which starts to make a difference at 1,000 (ie 10 x 100) yards when it's nearly 10 1/2 inches (10.47") rather than 10.

Why use MOA instead of inches? Think about changing from a 100 yard scope zero to shooting at a target 1,000 yards away. You have the MV for the load, you have the BC (ballistic coefficient) for the bullet. Feed them into a ballistics program and it gives the bullet drop over that distance with this zero setting, which becomes the 'come-up' needed on the sights. Saying the strike is predicted to be 366 inches low if the sight setting is left unchanged isn't really helpful. That's 35-MOA though, and on an MOA calibrated scope, it's an easy and relatively foolproof way of making the adjustment change. On the Sightron Series III target scopes I use, there are 15-MOA per full turret rotation, so I would turn the elevation turret through two full turns from the 100 yard setting, then go 'up' another 5-MOA. This and many such modern scopes use large externally marked turrets showing full MOA with a numbered large mark and intermediate smaller quarter-MOA hash marks.

For known distance prone deliberate shooting such as Target Rifle and F-Class, most competitors use an appropriate plotting sheet which places a correctly dimensioned target representation over a 1-MOA grid allowing easy calculation of both corrections and wind effects. The standard NRA TR ringed target which is what is most likely to be used in general target shooting on fullbore ranges has a 10.5" 'V Bull' (1-MOA); 21" 'Bull' (2-MOA), 42" 4-ring (4-MOA) for its centre in the 1,000 yard version. You take your first shot at it on your predicted setting and find you're high, level with the top of the 4-ring and way off to one side because of the wind conditions. The plotting sheet allows you to easily convert the error into an MOA change on the sights - say drop the elevation by 1 1/2-MOA or 6 clicks on most scopes or iron target sights (double that on models with 1/8-MOA adjustments) and move the windage by three or four MOA as determined by the grid on the sheet.

F-Class uses much smaller targets than the NRA standard (rings are half the diameter which equates to quarter the area). To see a plotting sheet calibrated in MOA, go here:

http://www.gbfclass.co.uk/index.php/hom ... ing-sheets

and you can have a look at the F-Class versions for different distances. The principle is the same though for all targets even though their dimensions might be different. Competitive shooters don't think inches but MOA. A short-distance sporting shooter is more likley to think inches and do the inch per 100 yards computation inside his or her head. Take a 150 yard shot at something and see the strike a bit high, think that was maybe six inches above the aiming mark, it's 150 yards (1.5 x 100), divide 6 by 1.5 and the scope setting is 4-MOA too high ... adjust downwards by that amount and try again.

MOA isn't the only such system. Military, police, and CSR etc competitors usually favour MilDot sights which are calibrated in miliradians

Great writeup :)

[Laurie]

Spot the 'deliberate mistake' though (as per Capt Mainwaring!). I should have said turn the [15-MOA] elevation turret on the Sightron up two full turns (= 30-MOA) + another 5-MOA. Having said 'relatively foolproof' that's just the sort of mistake people make on the range when setting up - get a turret setting a full turn out which is of course disastrous at longer distances.

Thanks to Halodin for pointiong the error out.

[Maggot]

[quote="TattooedGunI think this is more detrimental to someone asking how it works in simple terms than any other message I've ever read? What the hell are you even talking about?[/quote]

Well, actually what the hell I am "even" talking about was a tried and tested rule of thumb that basically provides a simple, easy way to move from one range to another and stay on the board (with a .308 rifle)

That is what the hell I am even talking about.

I was not attempting to explain the minute of angle, subtension, etc etc.

I grant you that it is not smack on, but the idea is that all you need to remember is that for each range from 0-1000 all you need to remember is 1,1,2,2,3,3,4,4,5,5 and add each value in moa to the elevation set as you move from distance to distance.

The problem is as I say I realise I had forgoten whether it starts at 2 or 1....muppet!! But I will look it out and put it up here as it can come in handy.

So, you are at 400, to go from 400-500 you ad 3MOA...ONO.

I tried it right out to 900 and it worked perfectly well but I am damned where I saw it, I think from memory it was in some sort of manual that I am clearly too fecking ignorant to understand. Its written in my notebook so I check that out.

The point is though that when you manage to shake yourself free from Ipads, phones, apps, and all the other trappings, the old basic rules of thumb work (when the batteries run out or your mate aint there).

It is rough, ready, but something that will stop people wasting ammo or more likley getting booted off the firing point cos they cant hit the board to even register an adjustment....but again, not being the font like your good self....what the hell would I even know.

And what hell is all this "even" s***....?

[Maggot]

Spot the 'deliberate mistake' though (as per Capt Mainwaring!). I should have said turn the [15-MOA] elevation turret on the Sightron up two full turns (= 30-MOA) + another 5-MOA. Having said 'relatively foolproof' that's just the sort of mistake people make on the range when setting up - get a turret setting a full turn out which is of course disastrous at longer distances.

Thanks to Halodin for pointiong the error out.

Dont worry Laurie, the only issue I would have was you nicking my nickname...there I was, full kit, CEFO, covered in mud chuntering accross a ploughed field and the Mainwaring name followed by the theme tune stuck (Actually the reference was to Jo Walker but I dont smoke).

I know what you mean with the Sightron. When I sold my LRTD with my Dolphin, it had a 10 MOA turn on it....the current one has a 15....how many times has that had me?

[RobB]

Regarding being a full turn out...that happened to me on windage last Saturday. Was on '3' MOA from '0' from last shoot but forgot that even though I was shooting at only 600 yards the previous time I actually had 7MOA dialled in (it was windy that shoot). So went back to wrong '0'. Lesson is always return to zero at the end of the day.
I have the MOA drop for all the distances I shoot written on my ammo boxes. I have a ballistics app on my phone but as Maggot says....battery could fail, drop or lose it. It will at least get be on the paperwork.

[TattooedGun]

I think this is more detrimental to someone asking how it works in simple terms than any other message I've ever read? What the hell are you even talking about?

Well, actually what the hell I am "even" talking about was a tried and tested rule of thumb that basically provides a simple, easy way to move from one range to another and stay on the board (with a .308 rifle)

That is what the hell I am even talking about.

I was not attempting to explain the minute of angle, subtension, etc etc.

I grant you that it is not smack on, but the idea is that all you need to remember is that for each range from 0-1000 all you need to remember is 1,1,2,2,3,3,4,4,5,5 and add each value in moa to the elevation set as you move from distance to distance.

The problem is as I say I realise I had forgoten whether it starts at 2 or 1....muppet!! But I will look it out and put it up here as it can come in handy.

So, you are at 400, to go from 400-500 you ad 3MOA...ONO.

I tried it right out to 900 and it worked perfectly well but I am damned where I saw it, I think from memory it was in some sort of manual that I am clearly too fecking ignorant to understand. Its written in my notebook so I check that out.

The point is though that when you manage to shake yourself free from Ipads, phones, apps, and all the other trappings, the old basic rules of thumb work (when the batteries run out or your mate aint there).

It is rough, ready, but something that will stop people wasting ammo or more likley getting booted off the firing point cos they cant hit the board to even register an adjustment....but again, not being the font like your good self....what the hell would I even know.

And what hell is all this "even" s***....?

That's a slightly better description. Do me a favour. Go back to your original post and re-read it. See if it makes sense if you assume that you have no idea what you're talking about. You can connect the dots because you have the idea already in your head what you're talking about. As someone who was reading it, it makes no sense whatsoever.

Take offence, if you like, but I wasn't the only one who looked at it and had no idea what you were talking about.

The problem wasn't whether you start at 1 or 2, it was the complete lack of any description to what you were talking about.

Someone who already knows the system might look at it and understand. To someone who is new to the system you're describing it's just incoherent.

[North Star]

Once you have the basic information on how many minutes you need to come up for the various distances you will be shooting at, make a record of it! You will need to adjust these regularly depending such things as powder lot number, different primers you might want to try, different seating depths etc. The top shooters can be on target at 300 yards, then move back to 1000 yards and be in the bull on their first shot!

I shoot target rifle so the vernier scale on the sights makes it a lot easier check your elevation. I have a lot of admiration for scope shooters who have to make a note of how many revolutions they have made on their dials!

[channel12]

Hi Is there any websites that can explain moa in basic terms.I'm looking to work out how much to dial up from a 100 yrs zero.I'm sue this is basic stuff but I struggle with the calculations.thanks

I bet you now wish you had paid more attention during geometry lessons !

[RobB]

I'm looking to work out how much to dial up from a 100 yrs

If you know your bullet type (e.g. Berger 155.5 Match Fullbore) and your Muzzle Velocity (MV) I can send you a table from a ballistics programme (say every 100yrds out to 1000yrds). Won't be adjusted for temp, pressure etc but will be pretty close.

They are interesting to look at anyway.

[RobB]

Example of one....which may or may not display :)

I always find table of pictures really do speak a 1000 words.