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tenths of moa

D

Doug72

Private
Minuteman
May 21, 2018
11
2
I'm trying to determine how much difference .4 inches makes at 500 yards and greater. My JBM download, shows about .4 inch difference from a previous download. I tried the math, ("my worst enemy"); but here goes.

If 1 MOA = 1.047, then 1.047 X .4 = .4188 X 5 (500 yds) = 2.094 inches additional elevation/windage, yes or no. Where am I going wrong????

If by some miracle I might be correct, does this formula hold true for other 10ths of inches calculation; Or am I, all FUBAR.

Doug
 
You did the calculation to determine what .4 MOA is at 500 yards correctly but in the first part of your post you said that JBM showed a .4 inch difference at 500 yards between this latest download and a previous one. So first, which is JBM telling you, is it a .4 inch or a .4 MOA difference at 500?
 
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Trigger Monkey said:
You did the calculation to determine what .4 MOA is at 500 yards correctly but in the first part of your post you said that JBM showed a .4 inch difference at 500 yards between this latest download and a previous one. So first, which is JBM telling you, is it a .4 inch or a .4 MOA difference at 500?
Click to expand...
TM: Great question. These figures come from varying temperature or Baro differences. Not too significant. However, to your question, JBM shows for eg, -9.6 MOA adjustment on one printout. On the other, it reads 10.0 as an example. So to my question, it does sound like I need to make this .4 addition. Also if the plate target is, let say 4x4 inches, do I then halve the 2 inches to hopefully land dead center???
Thanks, good to know my foggy brain got the math right.

Doug
 
You need to learn to just use a scope and reticle before you worry about wasting your time with quantum mechanics. You dont need to know inches at all as they are completely irrelevant for an angular correction.
 
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Trigger Monkey said:
You did the calculation to determine what .4 MOA is at 500 yards correctly but in the first part of your post you said that JBM showed a .4 inch difference at 500 yards between this latest download and a previous one. So first, which is JBM telling you, is it a .4 inch or a .4 MOA difference at 500?
Click to expand...
Addendum to your first post. I am thinking ( do not want to ass u me) if it reads ie. 10 and the other 9.6 then is the 10th inches or as you pointed out moa. I do not know!! which in everyone's experience is it. TiA..........Doug
 
Ok, you were doing good until the addendum part....

First, with any ballistic calculator, junk in equals junk out so if you start playing with temps, pressures, humidities, then there are going to be variances. If one chart says 9.6 and the other says 10, it really doesn't matter because like I said it's a baseline that you need to true up at distance by actually shooting. Dial 9.75 MOA and let it eat. Adjust from there, record it, remember it.

Second, "I am thinking...if it reads ie. 10 and the other 9.6 then is the 10th inches or as you pointed out moa. I do not know!! which in everyone's experience is it."
Well what output value did you select in the drop down menu in JBM? If you had selected MOA then the output values would be in 1/10th MOA increments. If you'd selected inches then the output would be 1/10th inch increments, however those two values are not even close to the same thing. .4 inches at 500 yards is about .08 MOA at that distance whereas .4 MOA at 500 yards is 2.094".
 
Trigger Monkey said:
Ok, you were doing good until the addendum part....

First, with any ballistic calculator, junk in equals junk out so if you start playing with temps, pressures, humidities, then there are going to be variances. If one chart says 9.6 and the other says 10, it really doesn't matter because like I said it's a baseline that you need to true up at distance by actually shooting. Dial 9.75 MOA and let it eat. Adjust from there, record it, remember it.

Second, "I am thinking...if it reads ie. 10 and the other 9.6 then is the 10th inches or as you pointed out moa. I do not know!! which in everyone's experience is it."
Well what output value did you select in the drop down menu in JBM? If you had selected MOA then the output values would be in 1/10th MOA increments. If you'd selected inches then the output would be 1/10th inch increments, however those two values are not even close to the same thing. .4 inches at 500 yards is about .08 MOA at that distance whereas .4 MOA at 500 yards is 2.094".
Click to expand...
Trigger Monkey
Got it!!!!!!!!! Yes my selections were in MOA. So this makes sense now. However, how did you arrive that .4 inches is about .08 MOA? Would you please show the math. Also in your shooting experience, since my scope is in 1/4 MOA, do suggest rounding down if less than .5 and staying at X.2 (=1/4 moa) or rounding up if greater than .5 MOA.
While this is simple for many of ya, it's a struggle at times for me. Very deeply appreciated.
Doug
 
Am I missing something here? Why does any of this matter when you can’t dial a tenth of a moa?
 
kriller134 said:
Am I missing something here? Why does any of this matter when you can’t dial a tenth of a moa?
Click to expand...
Kriller134,
Fair question. My response is, I was unclear what the Tenth position indicated. Now I know. Simple isn't it, when some one can clarify something for another.
 
1 MOA = 5.235"

.4"/5.235"=.076 MOA (.08 MOA)

I shoot with scopes in mils, round to the closest 1/4 MOA value on your scope. If the chart says 9.6 then I'd probably dial 9.5 on the scope, likewise if the chart said 9.3, then I'd probably dial 9.25. Again, the chart is a baseline that has to be trued to your rifle and ammunition, it will get you close but the bullet will tell the tale. Record your trued data and you can either manipulate the inputs in JBM to spit out more accurate data or create your own charts.
 
Trigger Monkey said:
1 MOA = 5.235"

.4"/5.235"=.076 MOA (.08 MOA)

I shoot with scopes in mils, round to the closest 1/4 MOA value on your scope. If the chart says 9.6 then I'd probably dial 9.5 on the scope, likewise if the chart said 9.3, then I'd probably dial 9.25. Again, the chart is a baseline that has to be trued to your rifle and ammunition, it will get you close but the bullet will tell the tale. Record your trued data and you can either manipulate the inputs in JBM to spit out more accurate data or create your own charts.
Click to expand...
Trigger Monkey
Ok got it! Ergo, 1 MOA = 1.047 X 5 = 5.235, .4/5.235 + .076 rnd'd =.08.
Thank you, thank you, thank you! As I've noted math has always been my bain. You guys are the greatest. Despite the humility of dumb questions, One can learn from others. If your less than 75+ then always keep an open mind. Those > 75 +, thanks for your acquired wisdom.

Doug-----Out
 
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