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Drop Chart Help Please

 
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  #1  
Old 05-07-2014, 11:20 PM
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Join Date: Aug 2012
Posts: 168
Drop Chart Help Please

I recently bought a .260 Rem. and Nightforce ACTAR MOAR (minute of angle). I am new to dialing and would be very, very, grateful for some help.

Sighted in the scope at 100, 200, 300. Here are my dial numbers before making the 100 yard elevation adjustment zero on the dial.

100 1.75
200 3.75
300 6.25

After I move the cap to set 1.75 to zero, these will be my dial numbers I believe.

100 0
200 2
300 4.50

How do I know from this data what my scope settings will be out to 500 yards given my muzzle velocity of 2,556 fps. and bc of .585

I ran a chart on my Sierra Infinity Ballistics Software but it only tells me drop and such without any conversion for the scope dial numbers at each yardage. I don't understand how adjustments change every hundred yards (ie. 1 click is 1/4 inch at 100 yards and 1/2 inch at 200, etc.) I think. So, how do I convert my drop chart based on inches from the Sierra program to dial numbers on my scope?

Also, a graph I did says it will be moving at 1,900 fps. at 500 yards. Will I have enough speed to shoot this bullet out to 1,000 yards before it feels the effects of the transsubsonic barrier or whatever the speed is that causes instability dropping below the speed of sound.

Please help.
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  #2  
Old 05-07-2014, 11:52 PM
Platinum Member
 
Join Date: Feb 2011
Location: Halfway between Lubbock and Dallas
Posts: 4,586
Re: Drop Chart Help Please

Quote:
Originally Posted by 17Fireball View Post
I recently bought a .260 Rem. and Nightforce ACTAR MOAR (minute of angle). I am new to dialing and would be very, very, grateful for some help.

Sighted in the scope at 100, 200, 300. Here are my dial numbers before making the 100 yard elevation adjustment zero on the dial.

100 1.75
200 3.75
300 6.25

After I move the cap to set 1.75 to zero, these will be my dial numbers I believe.

100 0
200 2
300 4.50

How do I know from this data what my scope settings will be out to 500 yards given my muzzle velocity of 2,556 fps. and bc of .585

I ran a chart on my Sierra Infinity Ballistics Software but it only tells me drop and such without any conversion for the scope dial numbers at each yardage. I don't understand how adjustments change every hundred yards (ie. 1 click is 1/4 inch at 100 yards and 1/2 inch at 200, etc.) I think. So, how do I convert my drop chart based on inches from the Sierra program to dial numbers on my scope?

Also, a graph I did says it will be moving at 1,900 fps. at 500 yards. Will I have enough speed to shoot this bullet out to 1,000 yards before it feels the effects of the transsubsonic barrier or whatever the speed is that causes instability dropping below the speed of sound.

Please help.
Read the insert which came with your scope or go to the NF website. All you need to know are the graduations

If each click is .25MOA then the number 1 will be 1MOA. The number 3 plus 2 clicks would be 3.5 MOA etc.

Run your data out to 1,000yds. It will tell you if you are nearing the sonic barrier at that range. It won't be.
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  #3  
Old 05-08-2014, 09:08 AM
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Join Date: Dec 2011
Location: Vandergrift PA
Posts: 1,193
Re: Drop Chart Help Please

and Remember to verify. the B.C you have will change when the bullets fired. that's why you can put all perfect data into a drop chart and have a perfect 100 yard zero, and then go out to 1000 and the chart be off maybe 1MOA. I always chrono for ES and SD shoot the rifle In at 100 then take it out to 850+ and get a real number. then adjust the chart to match the real shooting results.
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  #4  
Old 05-08-2014, 09:15 AM
Silver Member
 
Join Date: Aug 2012
Posts: 168
Re: Drop Chart Help Please

Quote:
Originally Posted by WildRose View Post
Read the insert which came with your scope or go to the NF website. All you need to know are the graduations

If each click is .25MOA then the number 1 will be 1MOA. The number 3 plus 2 clicks would be 3.5 MOA etc.

Run your data out to 1,000yds. It will tell you if you are nearing the sonic barrier at that range. It won't be.
Thank you! Read everything that came with the scope and no info was included on this for some reason? I was confused thinking what you describe wouldn't work because 1 click 1/4 is .25 at 100 but .50 at 200, etc.?
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  #5  
Old 05-08-2014, 03:41 PM
Platinum Member
 
Join Date: Feb 2011
Location: Halfway between Lubbock and Dallas
Posts: 4,586
Re: Drop Chart Help Please

Quote:
Originally Posted by 17Fireball View Post
Thank you! Read everything that came with the scope and no info was included on this for some reason? I was confused thinking what you describe wouldn't work because 1 click 1/4 is .25 at 100 but .50 at 200, etc.?
No, 1 MOA is 1 MOA at any range. The number of inches grows but the angle remains constant. Minute Of Angle.
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Without the First and Second Amendments the rest of The Constitution is Meaningless.
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  #6  
Old 05-12-2014, 07:43 PM
Silver Member
 
Join Date: May 2012
Location: Lebanon County PA
Posts: 177
Re: Drop Chart Help Please

I used to run Sierra Infinity, and I recall the output could be set for MOA instead of inches.
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