Long range sighting advice?

[BerettaRacer]

Hi,
This situation came up this week and looking for advice from more experienced long range shooters. I'm going to present two scenarios, and let me know what you think. The base line equipment will remain the same, but the situation will change, numbers will be rounded out for convinience.

Base line equipment:
-Gun is correctly sighted in at 100 yds.
-Ballistics charts show a 5" drop at 300 yds.
-Scope has 1/4 moa adjustments.

Scenario #1:
First shot is dead on X at 100 yds. Ballistic chart shows 5" drop for 300 yds, so with a 1/4 moa/click scope (1/4 x 5= 20 clicks), you raise the scope 20 clicks, second shot is exactly 5" high at 100 yds, and , with a 5" drop, should give you a perfect X at 300 yds.
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Scenario # 2:
You know your gun is sighted correctly at 100 yds, so you go srtaight to the 300 yd line. First shot is 5" low, exactly as ballistic charts said you would be. Now, to correct, each click of a 1/4 moa scope at 300 yds is 3/4" (3/4 x 5=7clicks) so you raise the scope 7 clicks to get your X.
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Which is correct 20 clicks in #1 or 7 clicks in #2? (Extra credit for showing your work, lol)


I haven't said anything about a 308 or 223 or anything else. It could be a 400 gr paintball.
The specifics given are a 5" drop. Period. Doesn't matter what the projectile is. It's a 5" drop.

The issue is, do you adjust for 5" over X at 100 yds with 20 clicks, or raise up the 5" drop at 300 yds with 7 clicks.




Thx

 

[GJgo]

#2. Inches & MOA only share the same values at 100yds. Thus, it is more effective to think in terms of MOA when reaching out.

 

[USP45T]

#2. 7 1/4moa clicks moves u 5.25" at 300yds.

 

[Hud]

Based strictly on how many clicks to come up 5" at 300, I agree with #2.
Altho, for the ballistics to show only a 5" drop at 300, the whatever projectile would have to have a pretty good BC & a muzzle velocity of around 4000 fps.

 

[lions]

Edit: Nevermind, got it backwards.

 

[MCMXI]

#2. 7 1/4moa clicks moves u 5.25" at 300yds.

Well, not exactly. 1 MOA at 100 yards = 1.047", therefore, 1/4 MOA = 1.047"/4 = 0.262" at 100 yards. One click (1/4 MOA) at 300 yards = 3 x 0.262" = 0.785". 5"/0.785" = 6.367 clicks. In other words, you'll have to settle for 6 clicks = 6 x 0.785" = 4.71" so you'll be just over 1/4" low at 300 yards.

Based on your first scenario, if you lower the reticle by 20 clicks (1/4 MOA), you'll be 14 clicks too high. In other words 14 clicks is 14 x 0.785" = 10.99" so you'll be (10.99" - 0.29") high = 10.70" high at 300 yards.

If my math is messed up it's because I'm enjoying a bottle of Moet & Chandon (Imperial) with a "friend" but good luck to you.

 

[Uncle Mike]

Which way do you like it? If scenario #1 works well for you, then that be the one to use.
If scenario #2 floats your boat use #2.
You see, it really does not matter how you get there, just as long as you get there!

I would use #1.

 

[USP45T]

Yes, not exactly. I dropped the 0.047. You dropped the 0.00025 from your 1/4moa X 3 calculation, lol. 6 clicks would closer to 5" than 7 clicks at 300yds. 7 clicks would move you 5.49675". He said he was rounding for our convenience.

 

[USP45T]

....

 

[Hud]

So BerettaRacer ,
Did we pass the audition?

 

[BerettaRacer]

So BerettaRacer ,
Did we pass the audition?

Actually, I don't know what the correct answer is, thats why I'm asking.

I live near a 100yd range, and next weekend we're supposed to go shoot a 300yd bullseye match at another range up state. I don't like the idea of driving halfway across the state to show up at a match with an unsighted rifle, I'd at least like to be in the ballpark. It's not going to be much fun if my shots are dinging the berm while other shooters are scoring points.

Originally I had been leaning more towards #1, but lately I'm leaning more toward #2.

 

[Uncle Mike]

MOA Correction:

Bullet Movement @ Target (in inches), divided by, Range to Target in Yards (use MOA Value) = Come-Up in MOA

Come-Up in MOA, divided by, Scope Adjustment Value = Number of clicks to adjust turret on your scope.

Example......

1) So, at 300y your bullet dropped 5" (5"bd)..... MOA value for 300y is 3.141"(1.047" X 3) ......................1 MOA at 100y is 1.047"

2) 5"bd/3.141" = 1.5918 (this is your 'Come-Up Value' in MOA) we will call it 1.6

3) 1.6/.25"(your scope adjustment value,@100y) = 6.4 Clicks UP (This is how many 'Clicks' you need to move your turret knob)

To check it:
1) 6.4 clicks X .25"(scope adj. value) = 1.6(MOA)

2) 1.6(MOA)X 3.141"(MOA value for 300y) = 5.025" ( Vertical Bullet Movement, in inches, at 300y)

This is the long way to do it, but it helps to see all the little steps for some people.