Rifle Scopes Drop chart help

[MasterPredatorHunting]

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.

 

[RobertB]

Is there an option to change your units to MOA? Don't go with inches, go with an angular measurement like mils or MOA (in your case MOA of course). I have used that program and I know it will do it but don't have it here with me. FYI, with that scope you have just use your reticle to make adjustmnets. Don't think in inches. Only think in MOA. You will be better off and its much easier.


Good luck

 

[FLIGHT762]

It would be beneficial for you to start learning to use a ballistics software program and use it in MOA and dial accordingly for your ATACR. Since I don't have an I phone, droid ,etc. I use JBM Ballistics on the net for free. It takes a bit of learning, but it is very easy to construct a very useable drop chart.

If you are a bit of a techie, there are a bunch of ballistic software programs out there for the I phone etc.

 

[AR is for Argyle]

Hopefully attached is a screenshot of sierra software. *EDIT it is too small of an image

If you select "normal trajectory" under "trajectory" at top tool bar: The column labeled "bullet path 1moa" is the moa elevation you need to dial or holdover.

If it says 2.2, you hold or dial 2.2 MOA elevation, or 2 1/4 if you have 1/4 Minute adjustments

Do get the number of clicks, *which I don't recommend, You can also click on trajectory on the top bar, go down and then select minute angle, then 1/8 moa clicks ,1/2 clicks, or 1/4 etc .

 

[MasterPredatorHunting]

could not get your image large enough to see...

 

[Beiruty]

A simpler math is each 1" at 100 yrd is almost 1 MOA, 2" at 200 yd is almost 1 MOA.
So the simple formula is number of inch up divided by the distance to target is your MOA within 5% of true MOA up.

 

[HuDisCo]

We use exbal. It's only a starting point though. Use ammo that has a low velocity spread when subjected to varying temperature. Once you have a dope sheet from exbal or a similar program keep refining it based on your range data.