The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Laurie wrote: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

Laurie wrote: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 wrote:

TattooedGun wrote: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***....?

nearly there wrote: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

nearly there wrote:I'm looking to work out how much to dial up from a 100 yrs