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Pizzaguy Member
Joined: Oct 03, 2010 Posts: 34 Location: Oklahoma
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Posted: Mon Oct 04, 2010 5:07 pm Post subject: Minute of Angle - All you need to know. |
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I see a lot of people that talk about Minute of Angle (MOA) and then use the wrong terminology or are not real sure what it means. So, with your indulgence, I’d like to talk a little about it. First my qualifications, why should you listen to someone that doesn’t know what they are talking about? I’m a NRA and Law Enforcement firearms instructor (including long range,) as well as a former National Guard Governor’s twenty shooter. I regularly shoot at 1000 yards to keep on top of my game. Now on to the meat of it. I will be taking writings from other sources and mixing them together with my own experience, so please if I quote something you already read don’t point it out, I already know that.
Minute of Angle….
To understand what MOA means we must look at a circle. There are 360 degrees in a circle. There are 60 minutes of arc in one degree. So with 360 degrees X 60 minutes of arc = 21,600 minutes of arc in a complete circle. The circumference of a circle = 2πR. R = the radius of the circle and π = 3.1416. Now that everyone is good and confused I’ll tell you what that means…..
21,600 MOA = 2 X R (3.1416). What that means 1 = .0002908R. What this means is for any radius (or range) one minute = .0002908R. So what? I’m getting to the so what, bear with me that was the why, I’m getting to the how. So if R = 100yrds which is 3,600 inches, this means that one minute at 100 yrds is .0002908 X (R) 3,600 = 1.047. Now 1.047 is the true MOA “drop” everyone calls 1” MOA. This means at 100yrds 1MOA = 1.047, at 500yrds 1MOA is 5.235” and at 1000yrds 1 MOA is 10.47”.
For normal shooting 1 MOA = 1” but if you are doing the math for longer shots I would suggest using 1.047 as it will make a difference on the cold barrel shot.
Alright here is a quick test to see if you are following along so far. Let’s say your rifle is zeroed at 100yrds. Now you want to shoot the 450yrd plate. Our range card says that the elevation (Of this gun) is 9.25MOA@450yrds. Now we know at 450yrds 1MOA = 4.5” so to do the math (9.25 X 4.5) = 41.6” right? Right (trust me) So our scope has ¼ minute adjustments you would have to dope (or dial) 37 “clicks” to have point of aim point of impact at 450yrds. Let’s talk about scopes for a second.
Scopes come in all sorts of varieties, and I’m not going to go into what you should or should not use. It really is personal preference. I use Army mil dots. There are Bullet Drop Compensators (BDC), USMC mil dots, and a number of other “ideas”. I was trained to use Army mil dots so that’s what I use. The only recommendation I can make is pick ONE and stay with it. I don’t care what it is as long as it works for you. Clicks, I see SO MANY people at the range that have NO IDEA what they are and what they mean. It will be on your scope if it’s a ¼ or 1/8 MOA per click. Now let’s go back up to our chart. If 1MOA is 1” @ 100yrds, 1 click (1/4 Scope) = 1/4” @ 100yrds. This means at 200yrds it’s ½”, at 300yrds it is ¾” at 400yrds it is 1” and so on.
Try to think in minutes instead of inches. At a 100yrd target your bullet impact is 3” low, this is equal to 3MOA. So at 800yrds your bullet impact is 24” low this is ALSO 3MOA. The same 12 clicks are required to bring bullet impact to center mass in either situation. If you think in minutes 1” = 1MOA @ 100yrds the same as 8” = 1MOA @ 800yrds.
Last edited by Pizzaguy on Tue Oct 05, 2010 5:13 am; edited 6 times in total |
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Pizzaguy Member
Joined: Oct 03, 2010 Posts: 34 Location: Oklahoma
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Posted: Mon Oct 04, 2010 5:09 pm Post subject: Re: Minute of Angle - All you need to know. |
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I’ll get into ranging will mil dots, how to judge wind, range cards and the rest of it in the near future. After I see the feedback I get from this post.
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Mon Oct 04, 2010 7:16 pm Post subject: Re: Minute of Angle - All you need to know. |
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Pizzaguy, I'll be interested in following your discussion. My only feedback so far is it will be easier to read if you group you information into one post instead of 7.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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Elvis Super Member
Joined: Jul 27, 2008 Posts: 9253 Location: south island New Zealand
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Posted: Mon Oct 04, 2010 9:49 pm Post subject: Re: Minute of Angle - All you need to know. |
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Pizzaguy follow you so far. all good info.
_________________ You shot it You pluck it !
Them who eats the most duck eats the most feathers! |
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Vince Site Admin
Joined: May 25, 2005 Posts: 15715 Location: Brisbane AUSTRALIA
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Ominivision1 Super Member
Joined: Sep 20, 2010 Posts: 2984 Location: Iowa
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Posted: Tue Oct 05, 2010 1:24 am Post subject: Re: Minute of Angle - All you need to know. |
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Good discussion.
_________________ Regards
Limitations are but boundaries created inside our minds. |
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Pizzaguy Member
Joined: Oct 03, 2010 Posts: 34 Location: Oklahoma
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Posted: Tue Oct 05, 2010 5:12 am Post subject: Re: Minute of Angle - All you need to know. |
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slimjim wrote: |
Pizzaguy, I'll be interested in following your discussion. My only feedback so far is it will be easier to read if you group you information into one post instead of 7. |
I was worried about exceeding a word count limit per post. I'll use the spots I just made to add more information, please leave them there, thanks!
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Tue Oct 05, 2010 6:47 am Post subject: Re: Minute of Angle - All you need to know. |
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Thanks for condensing. I would just delete the post that are now empty. Otherwise, people won't know when you make new posts.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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Pizzaguy Member
Joined: Oct 03, 2010 Posts: 34 Location: Oklahoma
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Posted: Tue Oct 05, 2010 7:06 am Post subject: Re: Minute of Angle - All you need to know. |
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ok, delete them please
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Dawgdad Super Member
Joined: Feb 08, 2006 Posts: 1065 Location: On the Prairie
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Posted: Tue Oct 05, 2010 7:39 am Post subject: Re: Minute of Angle - All you need to know. |
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Pizzaman - good primer for a beginner to understand what shooting more than 100 yards at a time takes.
I shoot SR Highpower and take for granted that every body will grab a knob and crank in windage and elevation to make the center shot on the first pull. I do the same with my hunting scopes. I have the 4"point blank zero set for shots under 300 and have a stock chart with come ups and windage guestimate for longer ranges. This one is for my SR but you get the idea of what goes on the stock chart.
I used mil dots and a Mildot master for a while but found a laser range finder and the stock chart to be a lot faster.
_________________ Alcohol, Tobacco and Firearms should be a convenience store, not a government agency... |
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Pizzaguy Member
Joined: Oct 03, 2010 Posts: 34 Location: Oklahoma
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Posted: Tue Oct 05, 2010 12:21 pm Post subject: Re: Minute of Angle - All you need to know. |
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Mildot master is great if you know how to use it. I have a range card on all my guns, however I have found an awsome app for the iPhone/iPod Touch. It's called iSnipe and if you shoot lond range it's a MUST. I think I paid $25 for it and I have used it to make cold bbl shots out to 1200yrds on guns that I have never shot that far before.
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shrpshtrjoe Super Red Neck Member
Joined: Jan 26, 2005 Posts: 2965 Location: Maryland
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Dawgdad Super Member
Joined: Feb 08, 2006 Posts: 1065 Location: On the Prairie
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Posted: Tue Oct 05, 2010 2:03 pm Post subject: Re: Minute of Angle - All you need to know. |
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Does I-snipe use GPS to determine altitude and local weather conditions(air pressure specifically). You can get by on a MR target out to 600 without being real close on altitude and air pressure but a 1200 yard CBS shot you better have that factored in too. Are you shooting LR paper B-I'S a Dog target or a gong at 1200?
Probably the most important factor is your actual BC of the load you are shooting. I generally will shoot at 100-200-300-500 with one scope setting and play with the ballistics program BC values until they match my trajectory. Very few bullets match published values. Again really not a huge factor out to 600 but after that...
Once you have the correct BC (not the published one) and the other factors figured out I am always pleased how close the ballistics programs come to giving proper dope. Physics is Phun!
Any way getting ahead of the rest of the class---carry on professor.
_________________ Alcohol, Tobacco and Firearms should be a convenience store, not a government agency... |
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Pizzaguy Member
Joined: Oct 03, 2010 Posts: 34 Location: Oklahoma
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Posted: Tue Oct 05, 2010 2:18 pm Post subject: Re: Minute of Angle - All you need to know. |
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Dawgdad wrote: |
Does I-snipe use GPS to determine altitude and local weather conditions(air pressure specifically). |
It sure does and with the 3GS or 4 (With built in compas) point it at the target and it will give you correct dope for the wind. It also will figure bullet drop based on the angle of your bbl. It's an AWSOME tool. Here is their web site www.isnipe.ca/
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Suzanne Super Member
Joined: Jun 27, 2009 Posts: 3323 Location: Eugene, Oregon
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Posted: Tue Oct 05, 2010 8:37 pm Post subject: Re: Minute of Angle - All you need to know. |
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Even I can understand your explanation THANK YOU >>>>MORE PLEASE!!!
Suz
_________________ May the moon keep you centered,
May the sun keep you dancing,
And the stars shed light on your dreams. |
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