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Mil Dots and Elevation Holds

12579 Views 14 Replies 7 Participants Last post by  m141a
I dont have all the information probably needed but in a nut shell im looking at purchasing my first Mil Dot scope to go on a nice .308 i have been eyeballing for awhile. Im planing on putting some HPBT Sierra 175Gr. rounds with a Muzzle Vel. of 2600 FPS. with a G1 Ballistic Coefficient of 0.496 through this rifle. Im trying to figure out the Elevation holds if i was to zero this rifle at 300 Yards due to my limited range access. I have been racking my brain for the past 2 weeks trying to figure all this out and im to the point where im just exhausted and frustrated on not being able to figure this out on my own. According to what i have found in my Ballistics book the PATH IN INCHES IS AS FOLLOWS : 100 yrds +2.2 , 200 yrds 0.0 , 300 yrds -9.1 , 400 yrds -26.1 , 500 yrds -52.4 , 600yrds -89.5 , 800 yrds -204.8 , 1000yrds -393.0
WIND DRIFT IN INCHES AS FOLLOWS : 100yrds 0.7 , 200yrds 3.0 , 300yrds 7.0 , 400 yrds 12.9 , 500yrds 21.0 , 600yrds 31.3 , 800yrds 60.2 , 1000yrds 111.2

If anyone can compute this for me and repost , as well as explain how you did it i would be very thankfulfor your time on this irritating issue im having. My book has an example with a .308 Fed. 168Gr. with a (600yrd Zero) as follows

yards Inches Mils
900 +158 +5.0
800 +88 +3.0
700 +36 +1.5
600 Zero Zero
500 -23 -1.25
400 -35 -2.5
300 -37 -3.0
200 -30 -4.0
100 -18 -4.5

Since the above chart is set for a 168Gr. bullet and zeroed at 600yrds , im only going to ASSUME that the round i want to use 175Gr. is heavier and that i want to zero at 300yrds there for the chart above would be incorrect. SO im asking for help on trying to figure this out cause my brain is fried , as much as i want a mil dot scope im just frustrated and about to give up with the mil dot idea. You all are my last hope on trying to "BREAK THIS DOWN BARNEY STYLE" for me. Thanks again
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As far as Mil-Dots go this is the basics. A Miliradian is equal to 3.6 minute of angle. Thus at 100 yards it is equal to approximately 3.6", at 200 about 7.2", 300 about 10.8" and so on. The reason I say approximately is that a minute of angle is not exactly 1" its actually just a hair over but don't worry about that right now.

If you are going to buy a mildot scope I will assume it will have some type of tactical or target turrets on it. In that case you will probably find it easier to just zero at 100 yards and then dial the elevation turret to the desired point for each shot at various yardages. For instance, if you are shooting the 168 grain bullet and are zeroed at 100 you would dial up 2 MOA to shoot 200, dial up 5 MOA for 300, 12 MOA for 500, you get the picture. You could also use the mildots on the scope to holdover the target but its more precise to dial up to the range you are shooting.

As far was wind drift goes the numbers you posted are for 10mph full value winds. You will have to read the wind and adjust accordingly. There is a simple formula you can use to get you in the ballpark which is: R x V / 15 = MOA adjustment or hold off. "R" is range in whole numbers such as "2' for 200 the "V" is wind velocity in mph and you divide by the constant of 15. Example: 3x10/15=2MOA. 2MOA at 300 yards would be 6" and as you can see from the chart you posted it is within an inch of the published data. This is where I like the mildots because I can just hold off for the wind and not adjust my turret for each shot since the winds can change quite a bit from shot to shot unlike the drops which are fairly constant unless there is a drastic change in temperature, humidity, slope angle, or altitude. I'm not sure if I gave you the info you wanted but I hope this helps.
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I forgot about the bullet weight issue. I don't know how far you are planning on shooting but the 168 is fine out to 600 yards. If you want to shoot further than that I would go with the 175. Of course it would not be a bad idea to try them both as you may find your rifle shoots one better than the other.
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