Indians For Guns

Hi
Well this topic may be well versed by the seniors of the forum, but I was intrigued by the terms MoA,Mrad and their easy application in shooting (Air rifle). Though in various articles dedicated to MoA, Mrad it was explained in details but could not find a universal & easily applicable formula to use it in shooting aid. The most difficulty I face is in zeroing a scope & once zeroed I use the mildots for poa & not MoA. But I was never able to know the calculations required to change the poa, like MoA, inches of adjustment, clicks required for changing the poi. What I used is trial & error method for known distances, but my shooting range is till 20yds so what I am to do if I have to take a shot beyond my known range & how to “Dope the Scope” to get poi=poa.
In the beginning I got all confused with so many factors, but slowly I got in terms with the equations. Here are the facts that have been shown in various articles related to the Minute of Arc.

We know that 1 MoA for our scope is rated as ¼, 1/8, ½, this means at 4,8 & 2 click adjustment of the turret respectively & the reticle will move 1inch at 100yards, So distance of 75yds, 50yds, 25 yds the MoA will be 75% of 1 MoA, 0.5 of 1 MoA, 0.25 of 1 MoA.
So we can use the formulas or determining the clicks requied
1) 1 MoA in inches=Distance(yards)/100
2) MoA adjustment=No. of inch of adjustment/inch per MoA at that distance
3) Adjustment in click on scope=No. of clicks per 1 MoA on scope X Moa Adjustment

For example, A person shooting at 175 yards & he is shooting 2inch low to the poa then how is going to adjust (clicks on the turret) to get the desired poi if his scope adjusts in 1/4 MOA.
He needs to find the 1 MoA in inches at that distance then by using the 1st formula
1 MoA in inches=Distance (yards)/100=175/100=1.75 inch.
Then using the 2nd formula he can find
MoA adjustment=No. of inch of adjustment/inch per MoA at that distance=2/1.75=1.14
So the no of clicks he will need can be done using the 3rd formula
Adjustment in click on scope=No. of clicks per 1 MoA on scope X Moa Adjustment=4X1.14=4.56 clicks.

Another one, if the person shooting at 50 yards & he is shooting 1inch low to the poa then how is going to adjust (clicks on the turret) to get the desired poi if his scope adjusts in 1/4 MOA.
1 MoA in inches=Distance (yards)/100=50/100=0.50 inch.
MoA adjustment=No. of inch of adjustment/inch per MoA at that distance=1/0.5=2
Adjustment in click on scope=No. of clicks per 1 MoA on scope X Moa Adjustment=4X2=8clicks.

Say we don’t know the distance of the target & we don’t know have rangefinder than we can guestimate the distance by measuring the mildots coverage of that known object (say a brick, dimension as 9X4.25X2.75 inch or 228X107X69mm)
So here the formula can be used for both metric & imperial
Distance(yds)= (Height of target (yds)/No. of mils covered)X(scope mag/10) X1000 =0.25/6X9/10X1000=37.5yds
(9 inch=9/36yds=0.25yds, the target covering 6 mildots).

Distance(mts)=( Height of target (mm)/No. of mils covered) X (scope mag/10)=(228/6)X(9/10)=34.2mts

We know that MilDot 6400 mils/circle whereas Milliradian or Mrad divides a full circle into 6,283 parts. So we can establish that 1Mildot=1.019Milrad, but for our ease of calculation we are considering Mildot=Milrad
We also know that Minute of Arc=1/21600 of a circle, so we can also establish a relation between Mildot & MoA. Therefore 1 MOA = 0.2908 MilRad for ease of calculation we will consider 1 MOA = 0.3 MilRad
Or MilRad=3.4 MoA

Now for the calculation part we can deduce that
For determining the no of clicks on the scope to compensate the poi to poa we can use
No of Clicks required=MilradX14 where Mrad=0.98 Mildot (considering Mildot=Milrad)
Here is a table of my shooting data where the datas of the first 5 columns are from ballistic calculator & the last column is used for calculating the datas manually

Dist Moa Mrad Inch Click Mil=Mrad Clicks=MradX14
10 -4.52 -1.31 -0.47 -18.1 -1.31 -18.34
15 -9.91 -2.88 -1.57 -39.6 -2.88 -40.32
20 -11.9 -3.46 -2.48 -47.6 -3.46 -48.44
25 -12.5 -3.64 -3.27 -50 -3.64 -50.96
30 -12.39 -3.6 -3.9 -49.6 -3.6 -50.4
35 -11.85 -3.45 -4.33 -47.4 -3.45 -48.3

So if I am not wrong then I guess we can use the formula simply to multiply the factor 14 to the mildot where the poi in respect to poa for scopes having 4 graduation adjustment of MoA for 1 inch @ 100 yds.

Secondly we can find out the deviation in poi to poa in terms of inch by using the following formula, where we can consider Mrad as to be mildot inrespect of poi to poa. This equation can also be used to measure the distance if poi to poa deviation is measured using a vernier calipers or any scale(Inch=MradXDistX36/1000).
Here the datas of the first three columns are from ballistic table

Dist Inch Mrad Inch=MradXDistX36/1000
10 -0.47 -1.31 -1.31X10X36/1000=0.4716
15 -1.57 -2.88 -1.555
20 -2.48 -3.46 -2.49
25 -3.27 -3.64 -3.276
30 -3.9 -3.6 -3.888
35 -4.33 -3.45 -4.347

Tried to calculate for making adjustments by using the mildots & distance, but ofcourse the calculations were made for same angle of shooting & scope magnification. I know these things might have been done way back & people might say having ballistic mobile applications, one doesnot need to consult such tables/calulations. But I would like to say that if we are aware of the basics then it gives pleasure to work out the unknown parameters, then you can always refer it with the ballistic calculator. I would like the senior members to shed some light & corrections required (if at all it is correct).
Regards Moulindu

Dear Moulindu,
You have done an nice research which none so far has done on forum.
It is surely a great guide for those who do long range shooting.
PCP owners may receive better help by your this post.

Basu

Very good post Molindu.....
i love to take long range shooting than short range shooting
In my view, The problem with our Indian shooters is mainly the two factors
1. CHRONOGRAPH - Only if we could know the velocity of the rifle with each pellets it would be better to estimate the pellet curve path. (i agree while using clicks it does not matter a lot like using mildots. But even a pellet will drop only 1 inch at 75 yards but when it reaches 85 yards it may drop 4 inches. ) do a chrono is necessary
2. Ballistic coeffcient of pellets (Indian pellets) this also plays a important role in long range shooting. Our Indian pellets has to go a long way in these fields.

These are just my knowledge they may be incorrect too....
I read these information through, FIELD TARGET forum and TED,s Videos on youtube

Regards

Basu wrote:Dear Moulindu,
You have done an nice research which none so far has done on forum.
It is surely a great guide for those who do long range shooting.
PCP owners may receive better help by your this post.
Basu

Thanx Basuda
Thanx Sathya

sathya.sniper wrote:CHRONOGRAPH - Only if we could know the velocity of the rifle with each pellets it would be better to estimate the pellet curve path. (i agree while using clicks it does not matter a lot like using mildots. But even a pellet will drop only 1 inch at 75 yards but when it reaches 85 yards it may drop 4 inches. ) do a chrono is necessary

Even the seasoned shooter use on field data n do not purely rely on ballistic application, but yes those applications give will u a approximate value, as there are various parameters which are fed in an assumptions, wind most likely which plays a major role. the chrono datas from chronoconnect or audacity are sufficient as we are not in for competition. I have used the audacity data for TX 200 provided by Basuda & put that into application till 50 yards & it is giving very consistent result with ballistic chart & field shooting. In this scenario you only have to know is distance....just shoot at desired distance, find out the mildot drop/ rise by the pellet from poa & then multiply by 14.....write it in a piece of paper for future reference...dial back to the previous setting & repeat the process for other distances.
In the equations I have incorporated Mildot & MoA(in turret clicks) for easiest field application & quick zero. I have seen many vdos on youtube explaining those fancy terms but nowhere could find direct relation to Mildot & clicks required. If you are into mildot then its fine, but if u like shooting using MoA (like those fancy sniper movie), then this equation can be used (without consulting ballistic application).

sathya.sniper wrote:Ballistic coeffcient of pellets (Indian pellets) this also plays a important role in long range shooting. Our Indian pellets has to go a long way in these fields.

I am bit relaxed in this aspect as Iam using JSB Exact pellet.
If you want to know the detailed equation & how i derived it let me know.
Regards Moulindu

Hi Sathya

sathya.sniper wrote:CHRONOGRAPH - Only if we could know the velocity of the rifle with each pellets it would be better to estimate the pellet curve path.

Your question kept me thinking,now we can do this by using this method you can find the exact clicks necessary for poi= poa, then from no. of clicks adjusted you can find MoA & No of Inch deviated at that distance by using the formula

MoA=(No. of clicks/4) (for scopes having 4 graduation /1 inch @ 100 yds) &
No of Inch deviated= (No. of clicks/4)X(Distance(yds)/100)

Explaining the datas from the earlier shooting table

Dist Moa Mrad Inch Click Mil=Mrad Clicks=MradX14
10 -4.52 -1.31 -0.47 -18.1 -1.31 -18.34

MoA=(No. of clicks/4)=18.1/4=4.525
No of Inch deviated= (No. of clicks/4)X(Distance(yds)/100)=(18.1/4)X(10/100)=4.525 X 0.1=0.4525

using either of these two equations you make a ballistic curve for various distances in a graph paper. Once you get that ballistic curve you can make a ballistic chart either using any of the parameters, Now you dont need chrono, pellet weight, ballistic coefficient & any other fancy equipment to make your own cheat sheet.

sathya.sniper wrote:Ballistic coeffcient of pellets (Indian pellets) this also plays a important role in long range shooting. Our Indian pellets has to go a long way in these fields.

Now you dont need this any more
Regards Moulindu

Great job....

This is indeed a great job for sure molindu..... Cheers
This one looks to be very good info so i will try these out and will inform the results for sure

Regards
-Sathya

Congrats Moulindu - Excellent study & experimentation
Giving this a clinical thought - It augurs very well for 'Fire Arms' where the gun & ammo are subjected to certain standards.
When it come to ARs we are faced with a host of variables....
> Spring piston ARs
> ARs with Gas rams
> PCPs
Then comes the most crucial input - The Pellets, their metal composition, weight, shape, aerodynamics etc....
Admittedly AR shooting is confined to 75 yards maximum & within this confined range to calculate the pellet drop is a daunting task....
Most of us have been adopting a trial & error method - but your patient & in-depth study has opened up a 'New Vista' making us wanting to go back to the "Drawing Board"
Well Done Bro
Briha

Thanks Brihaji
I have been shooting lately to back my theory with practical. There were few markers which i kept for the range i shoot(i predominantly choose target near a brick, so as to give me better range finding opportunity). I was shooting at 3 targets at different distance like 25,35 & 45 yards. 25 & 35 were easy but the 45 yards was a tough one as there was no indicators to judge the poi. So i took a shot at a boundary wall 45 yards away from my position. I took aim at the wall & the pellet impact was 1 mildot below, then according the formula i adjusted 14 clicks up & voilla, it was bang on target. I took 5 consecutive shots at the target with 100% accuracy, couldnt have asked more.
Regards Moulindu