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 September 25, 2013, 04:52 PM #1 j_bliss99 Junior Member   Join Date: September 24, 2013 Location: Arkansas Posts: 8 Short-Range MOA Before I ask this, you must all know that I am a freshman in high school and I am completely new to MOA. I need it for a physics project. Now that you know this, I'll ask the question. What are the steps for measuring MOA? I've looked all over and have not found a clear way to measure it. And to add to the challenge, I'll be using a pistol from anywhere between 10-25 ft. away from the target. And if you know that MOA isn't the best way for what I'm doing, could you recommend another way to measure accuracy? Thanks
 September 25, 2013, 05:24 PM #2 gothcopter Member   Join Date: June 15, 2012 Location: Georgia Posts: 45 National Shooting Sports Foundation has a nice page with a simplified explanation of MOA. Really, MOA is just another way of saying "one sixtieth of a degree". http://www.nssf.org/video/facts/MOA.cfm Be advised that their formulae for computing MOA are a simplification, so some computational error will be introduced. For example, the correct formula for computing number of inches (y) per MOA at 4 yards would be tan(1/60) = y/(4*36) --> y=0.0419 in whereas the NSSF formula (which is the same formula most shooters use) would yield 4/100 = y --> y=0.04 If you haven't had trigonometry yet, you're probably best off sticking with the NSSF formula.
 September 25, 2013, 06:01 PM #3 allaroundhunter Senior Member   Join Date: May 6, 2012 Location: Southeast Texas Posts: 1,670 There probably is a better method than worrying about MOA, but first we have to know what exactly it is that you are trying to measure.
 September 25, 2013, 06:21 PM #4 j_bliss99 Junior Member   Join Date: September 24, 2013 Location: Arkansas Posts: 8 If you want to know what my project is to help you get a better understanding of what I'm trying to measure, I am trying to see if the mass of a bullet affects the accuracy. So I am trying to measure the accuracy of a group of bullets
 September 25, 2013, 06:32 PM #5 Dave P Senior Member   Join Date: August 16, 1999 Location: North Florida Posts: 1,269 As they said, MOA is just one way to measure an angle. Just call it degrees, if you want. Can you measure the angle (hypotenuse to adjacent side) of a 3-4-5 triangle with your compass? Same idea with MOA. __________________ Go Trump!
September 25, 2013, 06:50 PM   #6
allaroundhunter
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Quote:
 Originally Posted by j_bliss99 If you want to know what my project is to help you get a better understanding of what I'm trying to measure, I am trying to see if the mass of a bullet affects the accuracy. So I am trying to measure the accuracy of a group of bullets
Well, MOA or any other system of measurement will work well. However, seeing as I highly doubt your judges will understand what an MOA is or you being able to completely explain it in the time you're given I wouldn't use it.

To test what you want, then you will probably want to test at 10, 25, and 50 yards. As opposed to a couple of feet. You won't see much difference at all at that distance. You will also want to be shooting 3 or more pistols probably (same caliber, same batches of ammo)

Also, how do you plan on testing the shooting?

 September 25, 2013, 07:31 PM #7 j_bliss99 Junior Member   Join Date: September 24, 2013 Location: Arkansas Posts: 8 I'm not sure I understand on what you mean by "testing the shooting." Would it be better to measure from the two farthest holes and just compare the number of inches for the groups? I will be making my own bullets for this, and I don't know if I can get my hands on any pistols other than the .38 Special snub-nosed my grandfather owns. I do have a contact in the police station, and he said he could take me to their range and help and stuff. They'd probably let me use a .22 or something like that. I don't know if it would just be easier to pick a different hypothesis.. this is all so confusing for a 14 year old
 September 25, 2013, 07:38 PM #8 allaroundhunter Senior Member   Join Date: May 6, 2012 Location: Southeast Texas Posts: 1,670 Well, every gun shoots the same ammo a little differently. So to actually test whether one weight of ammo shoots better than another it would be a more accurate (no pun intended) test if you have multiple firearms testing the same ammo. And I meant will you be shooting the guns off a rest, or will you have a rest to lock them in to so that you take shooter error out of the equation?
 September 25, 2013, 07:45 PM #9 James K Staff   Join Date: March 17, 1999 Posts: 24,135 Also note that MOA is an angle, not a distance or linear measurement. The fact that one MOA comes close to 1" at 100 yards is convenient, but pure coincidence. Your subject line is a bit of a misnomer. There is no such thing as a short or long range MOA. An angle is an angle, whether the lines forming it extend an inch, a foot, or a million miles. Jim __________________ Jim K
 September 25, 2013, 07:53 PM #10 Brian Pfleuger Moderator Emeritus   Join Date: June 25, 2008 Location: Western Colorado, finally. Posts: 19,107 No need to measure MOA, just measure in inches. A group size is measured as the farthest distance between the outer edges of the two farthest apart two holes, minus one bullet diameter. For example, if you fire 5 shots with your .38spl and 3 of them are touching in the center while 1 is a an inch low and left and another an inch high and right, your group size would be 2 inches minus 0.357, or 1.643 inches.
September 25, 2013, 10:30 PM   #11
Jim Watson
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Quote:
 I am trying to see if the mass of a bullet affects the accuracy.
Unfortunately, there are many variables that affect accuracy. Mass is only one, and probably not a major one.

 September 26, 2013, 10:02 AM #12 parttime Member   Join Date: August 25, 2009 Location: Minnesota Posts: 79 Accuracy and precision have different variables. In order to measure the precision of a firearm/cartridge combination you first have to eliminate the inaccuracy of the shooter. You can do this by holding and firing the firearm in a bench vise of some sort while using a selected group of cartridges. Firing X number of cartridges at various distances at seperate targets, measuring their point of impact as discribed in an earlier post then switching to a different set of cartridges and repeating. __________________ The wants of the many DO NOT outweigh my needs.
 September 26, 2013, 10:38 AM #13 g.willikers Senior Member   Join Date: September 28, 2008 Posts: 10,447 Wouldn't it be easier to show what you intend without complicating things. Just use the one gun and measure in easy to explain inches or millimeters. Using multiple guns introduces more variables. And measuring in MOA requires more explanation - and glazed over eyeballs from your audience. __________________ Walt Kelly, alias Pogo, sez: “Don't take life so serious, son, it ain't nohow permanent.”
September 26, 2013, 12:25 PM   #15
allaroundhunter
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Quote:
 Originally Posted by g.willikers Wouldn't it be easier to show what you intend without complicating things. Just use the one gun and measure in easy to explain inches or millimeters. Using multiple guns introduces more variables. And measuring in MOA requires more explanation - and glazed over eyeballs from your audience.
Except only 1 gun is not a large enough sample size to draw a reasonable accurate conclusion. Especially since guns shoot ammo differently. If you want to prove that one is inherently more accurate than another then it needs to do so in more than one firearm.

September 26, 2013, 12:26 PM   #16
DaleA
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Quote:
 Unfortunately, there are many variables that affect accuracy. Mass is only one, and probably not a major one.
Jim Watson’s remark above is correct BUT you want to do this so let’s see how it COULD be done and you can throw the above statement in as a disclaimer at the end of your write up of the experiment.

(This is just a summary of what Brian Pfleuger, g. willikers and others have mentioned.

1. Use just the one gun. Using one gun is a good thing. Multiple guns would mean testing each one with the different bullets at the different ranges. Too much work. One gun is better.

2. You said you are making your own bullets. This is good too. You can make them up and explain how you made them. I’m assuming you are making them up in different weights and you want to see if the heavier bullets are more accurate than the lighter bullets.

3. Shoot the bullets at the targets at different ranges. You said 10 to 25 feet. This is fine. Use some kind of rest for the gun and do all the shooting yourself (heck, this is why you want to do this in the first place, so you can do some shooting yourself) and do it the same way each time. Do it this way and report the results. This is a scientific experiment. Doesn’t really matter WHAT the results are just show how you got them and what they are.

4. Use a ruler to measure the groups. Measure them from edge to edge. Just that. Be your own scientist, measure all the groups yourself and measure them all the same way and you will have consistent data for your experiment. Then write up the results.

Bells and Whistles. (Only if you want to do it.)

If you have a geometry (I don't think you need trigonometry) fan amongst the judges you might explain that shooters like to use ‘minute of angle’ measurements and then explain what that is. I don't think you need trigonometry for this but you might want to explain the ‘trigger-nometry’ that you used during your shooting!

For sure you want to explain other factors that might affect accuracy and which might even nullify, override or invalidate the results you found. This is honest. If you want a list of other factors that affect accuracy the group here would be happy to provide them. But look at each one and see if it is or is not a factor in your experiment. That is, someone might say some guns are more accurate than other guns. But since you used the same gun in all your shooting this is not a factor. Someone might say that the model of the gun you used is known to be so inaccurate and inconsistent that it completely overrides the bullet weight differences. This would be a valid point if true but if you get some consistent groups with the same bullets you can say 'Well the gun I used IS consistent, so there. (But leave out the 'so there' comment.)

Good luck.

 September 26, 2013, 01:03 PM #17 Lt. Skrumpledonk Ret Senior Member   Join Date: May 30, 2012 Location: Oh, Jesus. Posts: 226 That can o' worms There are too many variables on why this bullet impacted here and that bullet impacted there. Many of us spend so much money on marginalizing those variables only to realize we will never eliminate half of them. We're talkin lunar-gravitational-pull-coefficient-zenith-drag-cosine-MOA-type-stuff
 September 26, 2013, 02:44 PM #18 Buzzcook Senior Member   Join Date: November 29, 2007 Location: Everett, WA Posts: 5,971 Just like to note that accuracy and precision are not the same thing in science. An experiment can have results that are accurate or precise or both or neither. For example when we shoot at a target we aim at the bullseye, or some other point of aim (POA). We can have have a very small group of hits close together but not close to the POA. We could have a group which is relatively close to the point of aim but not grouped close together. There could be a group that is both close to the POA and close to each other. Finally the bullet holes could be spread all over the target, which is the way I shoot. It might get you extra points if you make the distinction when you measure you targets. When you have your report typed up, please post it here. I can say without reservation that we are all interested in your results.
September 26, 2013, 06:32 PM   #20
dayman
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Quote:
 Did you know that with handguns, lighter bullets will generally strike the target lower than heavier ones, with the same point of aim? This would seem to be the opposite of what one expects to happen, but I assure you it is true. Heavier bullets move slower than lighter ones, so they ought to hit lower, but that is not the observed result. Why? A lot of experienced pistol shooters know the answer, but your physics teacher may not. I'm not going to tell you the answer (not yet, anyway) but it does involve the mass of the bullet, along with other factors. It is an application of physics, and ought to satisfy your school project requirements about that.
As both a teacher, and as a firearms enthusiast, I like it.
Also, it will be much easier to cover effectively within the bounds of a high school physics project, which - based on your age - I'm assuming is descriptive physics rather than anything calculus based.
And as a bonus, if/when you do take calculus based physics, you could re-hash it, and actually come up with an equation for where a bullet of a given weight would wind up.
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 September 26, 2013, 07:03 PM #21 James K Staff   Join Date: March 17, 1999 Posts: 24,135 Group size is conventionally measured from CENTER to CENTER of the farthest apart bullet holes. The reason is that measuring the distance from the outer edges would automatically increase the group size for larger calibers. If it is not easy to measure center to center, measure edge to edge and subtract the caliber. Jim __________________ Jim K
 September 26, 2013, 07:04 PM #22 j_bliss99 Junior Member   Join Date: September 24, 2013 Location: Arkansas Posts: 8 Thanks for all the help and suggestions, guys! Unfortunately, I have already turned in my proposal it was accepted about 2 weeks ago. However, I believe I might know the answer to your question, 44 AMP, if it is as simple as I am thinking; is it because the greater amount of momentum in heavier bullets keeps them going in a straighter line? I have managed to tweak my project a bit to where I'm using a rifle and not having to make my own bullets, if that helps any. And I'll be sure to post the final results! Thanks again!
 September 26, 2013, 07:23 PM #23 j_bliss99 Junior Member   Join Date: September 24, 2013 Location: Arkansas Posts: 8 Another quick question, any ideas on what rifle/caliber I should? Thanks again!
September 26, 2013, 07:26 PM   #24
Cowboy_mo
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Quote:
 Group size is conventionally measured from CENTER to CENTER of the farthest apart bullet holes. The reason is that measuring the distance from the outer edges would automatically increase the group size for larger calibers.
which is why most people subscribe to

Quote:
 No need to measure MOA, just measure in inches. A group size is measured as the farthest distance between the outer edges of the two farthest apart two holes, minus one bullet diameter.
However, there is an easier way to measure "center to center". Take your measurement from the outside of hole A to the inside of whole B and your measurement will actually be "center to center" without performing subtraction of 1 hole.

September 26, 2013, 07:43 PM   #25
Spats McGee
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Quote:
 Originally Posted by j_bliss99 Another quick question, any ideas on what rifle/caliber I should?
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