About any gun will shoot an inch group..Some with one shot! and others now and then...

Reference to hunting rifles:

Some will shoot 1" 3 shot groups and that's not too uncommon.

Darn few will shoot 1" five shot groups...

Fewer will consistantly shoot 1" five shot groups with all loads or most loads to the same POI..In 60 years of shooting I have only owned a couple of three that will do this, needless to say I still have them and I shoot them very little and mostly for hunting only..

Some how my question got mixed up with another post! Anyway my question is about MOA. I am new to reloading and I don't understand what that term means and how to measure it! Thanks for the help!!!!

MOA is minute of angle or minute of arc. There are 60 minutes in 1 degree of arc. A gun that shoots MOA or less will shoot within a circle that projected out is a minute of arc. At 100 yds this is very close to a 1" diameter circle.

Minute of Angle.
There are 60 Minutes in a degree.
IOW your measuring the angle between the 2 shots that are the furthest apart.

Measure from hole center to hole center of the 2 furtherst apart holes (easier to measure the outside to outside and subtract 1 bullet diameter, gives the same answer).
For most purposes the following is close enough.
1 MOA is approxamitly 1 inch at 100yd (1.037ish if your fussy). As it is a angular measurment, 3" at 300yd is the same MOA as 1" at 100yd.
1 MOA = 1/4" @ 25yd = 1/2" @ 50yd = 5" @ 500yd etc.

bkmstr,

Whilst the previous posters are certainly technicaly correct in terms of firearms, minute of angle (MOA) is an important concept. However, it has no relevance unless you are shooting groups. This came from benchresters.

The whole purpose of shooting a group is, for the purpose of hunting rifles, to see how consistently the rifle will shoot. Many people mistakenly think it is a measure of the shooter.

For a hunting rifle to consistently "group" MOA is virtually standard. As one poster put it if your rifle will do that then you've got a good rifle and one in which you can have great confidence in the field. Having said that the key here is "consistency". How good a group a rifle will shoot once is meaningless. That's why I shoot my rifles as often as I can (fortunately, I'm less than 10 mins from the rifle range).

While benchresters will not shoot less than 5 shot groups, this is not always possible with a light hunting rifle. i tend to shot 3 shot groups with my hunting rifles as there are a multitude of factors that make good (MOA) 5 shot groups out of a light hunting rifle difficult to achieve.

So a rifle that will shoot 3 shot MOA groups ( and all mine do) will shoot 3 shoots into a groups that measure:

.5" at 50 yards
1" at 100 yards
2" at 200 yards
3" at 300 yards
4" at 400 yards
5" at 500 yards
.....
10" at 1,000 yards

Hope this and the other posts assists.

Magnum

Just one more comment...

If you are shooting five-shot groups, and, if they average 1" over many groups, you can expect to see groups as small as 1/2" and as large as 1 1/2", just from normal random variation. One 1/2" group does not mean that you have a super rifle, and one 1 1/2" group does not mean something is wrong. As long as your groups stay within that range, you have no reason to believe that anything has changed.

I have no issues with the above but will expand on Magnum's comment a bit. In terms of dispersion the 1", 2", 3" deal is okay to understand the concept of MOA, but I dare say that it may not work exactly like that in real life, in the field or on the range. There are many issues at play that confound that representation, such as wind, bullet imbalance, twist rates, BC, and velocity deviation to name a few. Their effect at close range is small, but as the distance grows it is not necessarily a linear change. shooting a 10" group at 1000 yards is very much more difficult than a 1" one at 100 yards.

Denton's comment is a statistical perspective, and perfectly valid. Rifles have good days and bad days, particularly due to temperature changes and resulting changes in load performance. It is difficult to tune your loads in the field.

To add just another bit of MOA trivia to this debate.

The consistent MOA performance of a rifle can give you great confidence in your rifle and the longer the range (distance) the more difficult it is to achieve (with a light hunting rifle) as DigitalDan rightly observes.

However, what is really important to me is where my rifles shoot the first shot out of cold barrel. When I am preparing a rifle for a hunt and developing loads, after I have shot my groups and I am happy with the way the rifle shoots with then load I will use, I will then shoot one shot out of a cold barrel to where I want the rifle to shoot.

Today I have a range session for exactly that purpose. I am preparing for a hunting trip for pigs (boar in the US). I am using 150 gr Winchester silvertips in my M70 pre 64 fwt 308 win. My ultimate aim is to have the rifle sighted dead centre but 2" high at 100 yards. This will put it bang on at 200 yards and about 9" low at 300 yards. My hunt will take me into the channel country (of Australia) where the country is flat bush (not unlike the African plains) and shots can be long.

Regards,
Magnum

Just to add to the fray, here is my take on measuring rifle angular accuracy. But as the others have said, any rifle that can put three inside a one inch circle at 100 yards is a good shooting rifle!

Chris

1) MOA is Minute Of Angle.

100 yards = 3600 inches

sin ( x) is approximately equal to x for small x, and MOA is very small x.

1 minute = (1/60) degree [(3600 inches) sin ((1/60) degree)] = [1.047 inches @ 100 yards] = [2.094 inches @ 200 yards] =[.261 inches @ 75 feet]



But at the range where I am a member, the concrete markers in the earth where we can put target stands are in METERS.



1 meters = 39.3700787 inches



100 meters = 3937.00787 inches



[3937.00787 inches] sin [1/60 of a degree] = 1.452291 " =1moa @100m



My best group ever [the last one I shot with my 257 RAI] was .46" at 100m = .4 moa





http://www.google.com/groups?hl=en&lr=&ie=UTF-8&selm=b5sfai%24dsc%241%40grapevine.wam.umd.edu



Some people make fun of wallet groups.



But I'm not putting that group in my wallet where it could wear out, I am making a tag out of it, that I am putting on the gun, so when I die, the next guy to own that VZ24 will know how special that rifle is.

Clark, don't laff about "wallet" groups... One of the owners of the first shop I worked as a Machinist kept his best groups in his wallet and would pull 'em out every time he'd get a new one(we're members of the same shooting club) The funny part is as far as I know, he doesn't have any pics of his wife or son in there! Talk about a dedicated rifleman! He taught me alot of stuff including how ta barrel rifles, which ruined factory guns for me, permanantly!

Toolmaker

Thanks to All for the answers. I will take these comments to the range and see how everything adds up! Thanks!

Hotcore,


I have a math problem for you:
Three guys get told the dinner bill will be $30.
The each give the waiter $10.
The owner tells the waiter that the bill is really only $25.
So the waiter gives each of the patrons back a dollar and puts two dollars in his pocket as tip.

$30 paid minus $2 in the waiter's pocket is $28, but the $9 paid by each guy times three guys is $27, where did the extra dollar go?

Anyway,
100 meters = 3937.00787 inches
converts metric to old English system.

The "DEMOCRAT" thought it was TAX money and stuck it in his pocket!



I was out doing some mowing today and was trying to remember an old Logic Problem. Well, I remembered the problem, but wasn't able to remember the answer as I mowed. Once I get it so """I""" know the answer, I'll post it for everyone.



It is not fun when portions of memory become somehow deleted as we age.

techshooter,

I read through your page on evaluating accuracy and have difficulty with the definition of "actual accuracy" or "actual moa". The definition of accuracy as I understand it depends on the person defining it ie.3 shot, 5 shot, 10 shot...there is no one "standard"...or could you be speaking of "long run averages".



In any case, I thought you'd enjoy reading this (make sure the images in my first post come up. If no, do a <right click> then select "show picture");

Accuracy Evaluation Discussion



BTW, I love your webpage. I'll have to spend more time reading when I have more time.

A man 25 marries a girl 5. He's five times as old as his wife. When he's 30, she's 10. He's three times as old as his wife. When he's 40, she's 20. He's only twice as old as his wife. How long do they have to be married before they're the SAME AGE??

Clark,

The "lost dollar" is with the restaurant...

Quote:

---

but the $9 paid by each guy times three guys is $27,

---

If the tab was 24 dollars, and they each received 1 back, the lost dollar magically appears again. The cost per head is actually 8-1/3.



eldeguello,

Mathematical Solution;

Never...the age gap will always remain 20 years. As the Ages grow in number, the apparent difference appears to becomes aymptotic (converges, but never meets), because the scale is growing. But the absolute difference remains the same.



Practical Solution;

It would take 20 years + (time for 5yr old's father to find out + 10 seconds). 10 seconds after the 5 year old girls father found out, the 25year old would be dead and would cease to age. While the 5 year old would continue to age. In 20 years plus the above stated lag time, they would be equal in age.

Was looking at this article and found it interesting. Confused about one thing...you describe error in terms of a 1D normal distribution, but it would seem to me (unless you're doing some sort of sophisticated polar coordinates thing) that you need a bivariate normal. This would change the numbers a bit as to place a shot into a 1" circle, you have to do it on _both_ the x _and_ y axes and this gets you into joint probabilities.



Not a huge difference, but if you're using the 95% criterion for getting into the 1" ring, this means you'd have to actually go up to 97.5% (i.e., as 97.5% squared = 95%). In this area of the normal, that makes quantitative difference, certainly, though qualitatively you're dead on.



Now that I think of it, even polar coordinates would involve a joint probability distribution--flat one for theta and normal for r, but I wouldn't really know how to analyse that situation without a bit of study first.



Anyway, did you go bivariate and just not tell us, or is it univariate (or polar)? The 250 shot graph can really be read as reflecting a 95% or 97.5% distribution with the # of shots outside the ring (seems closeer fit to 95%) and so that's why I'm asking.

I'd bet some big money that EVERY Sako will shoot an inch from the factory...Most won't for 5 shots..

The answer is $25 in the till + $2 in the waiter's pocket + $3 returned to the patrons equals $30. There is no missing dollar.
Or stated another way, patrons paid $27 ($25 in the till & $2 in the waiter's pocket) + $3 returned still equals $30.