help me understand how to use my scope.

[henry1]

:)well i feel like a butt but, am tired of trying to figure this out.... i have watched a couple vids on you tube and thought i understood it good enough but went to the range the other day (in 20 mph gusts) and couldnt hit my gallon jug of water at 422 yds. Rifle is 26'' fact varmint bbl chamberd in 220 swift. load is accurate, under 1'' @ 100. Scope! Haha scope is a Vortex 6.5X20X40 with target knobs for ele and wind. on turret it says, 1 click = 1/4 MOA. As i understand it, at 400 yds each click is = to 1 MOA? Right? I use JBM calculations for my ballistics and it has an option for drop in MOA.... Surely that doesnt mean i can just dial to what the drop in MOA says on the paper? It has got to be less simple than that. lol I am really good at making simple things way to difficult so i guess it could be that easy... was goin to try to hit the range today but seems wind has already picked up so i guess well see how desperate i get. Thanks in advance! I look forward to your help!
Henry.

[bill2260]

Sight it in 2 inches high at 100 yards. Should only drop 4 or so inches at 400. One click on the scope moves the impact 1/4 inch at one hundred yards. If the wind is blowing 20 miles per hour you will have to give it some kyntucky windage and hold into the wind 6 inches to a foot at 400 yards. Good luck, Bill

[henry1]

Ya the ballistics program says that with a 20mph wind from a 90 degree angle it will move the point of impact 23.9 inch at 400yds. I have a turret on the windage too.... the program says 5.7 MOA to compensate for that crosswind. so....does that mean to adjust my scope to where it is about the 5.5 number on the windage turret? haha just a little confused is all. Thanks for the quick reply.
Henry.

[davemuzz]

Well, I have a Leupold with a custom turret on it for the elevation. It's really nice and works like a charm. But...and I think this is what Bill is saying....even though I have a windage turret (not the custom one....I saw no need for that) I don't use it. I will look at my ballistic data for windage on the program that's on my smart phone....but if it says to adjust 20" for windage....I just hold at what I believe is 20". It seems to work well for me.

[james86]

One moa is equal to roughly 1" at 100 yards. That same adjustment (one moa or 4 clicks on your scope) will move the point of impact roughly 4" at 400 yards. So JBM is saying to dial 5.7 moa because you need to make a 23" adjustment at 400 yards (5.7moa x 4 = ~23"). So when you dial that windage at 400, just move your target knob from the 0 position to the 5 3/4 position (23 clicks of the scope) and you got your windage compensation.

[Tch2fly]

... Haha scope is a Vortex 6.5X20X40 with target knobs for ele and wind. on turret it says, 1 click = 1/4 MOA. As i understand it, at 400 yds each click is = to 1 MOA? Right?

No, one click is ALWAYS 1/4 MOA, the subtended linear value changes (1/4 inch @ 100 yds, 1 inch @400 yds) TECH speak - MOA is an angular (non dimensional) measurement and subtends to a specific linear measure at a given distance.
What that means (as James86 stated) is 1 MOA is roughly equivalent to an inch at 100 yds and for every 100yd increase in distance it will increase roughly 1 inch. Think of it like a cone ...

As seen in the top graphic an inch is always an inch regardless of distance. The lower graphic shows MOA, being angular, always expands and can converter to a linear measure at a distance.

.... I use JBM calculations for my ballistics and it has an option for drop in MOA.... Surely that doesnt mean i can just dial to what the drop in MOA says on the paper? It has got to be less simple than that. ...

Yep, it is really that simple. ;D

[skypilot]

:) I use JBM calculations for my ballistics and it has an option for drop in MOA.... Surely that doesnt mean i can just dial to what the drop in MOA says on the paper? It has got to be less simple than that.
Henry.

Sounds like your setup(rifle,scope,barrel,etc.)do not match the JBM trajectory data(not unusual). Your setup may be droping more or less than JBM. Generally one has to shoot several actual ranges to determine the difference in your drop data and JBM's calculated data.

Also many scopes do not actually move the advertised 1/4 MOA or 1/8 MOA.

You probably will have to shoot @ 400(or whatever longest distance you plan to shoot in the future) get the difference in your setup's bullet drop and the JBM data. Do the same @ 300, 200 and 100.

Then adjust JBM's velocity and B.C. until JBM trajectory matches your data (trajectory).

You may also have to adjust JBM's elevation from .250 MOA to say .298 or .365 or whatever your scope "actually moves per click"are.

Now you have "Trued" the JBM ballistic data and your setup. Now when it says dial in X clicks or x MOA just dial in that come-up and send one.....watch the water jug dance ;D

Cheers