How to sight in a rifle - The proper use of variable power scopes

[Stainless]

OK I know this is elementary to you guys but I need knowledge. Just so you know, I've searched the threads to not waste anyone's time and still have many questions.

I am about to sight in my first long range gun. My question is how do I properly sight-in and shoot my rifles at various ranges using a variable power scope?

I have just read the parallax vs focus thread (great thread) for abouth the fifth time and I have a good understanding of what I should do to set my parallax corrections for different yaradges.

I will be shooting a 300 win mag out to 500yds initially.

I am just starting to handload under the instruction of my smith so I will be shooting factory loads for now.(Winchester XP3 or Hornady Custom in 150gr. are the likely rounds) I know the advertised drops for the ammo along with BC, velocity and energy.

The scope is a leup 6.5-20x50 LR/T Target Dot with the side parallax adjustment.

This is basically what I know. Variable power allows a shooter to increase magnification of the target.

What I don't know could fill volumes.

1) What power should be used in sighting-in the rifle at a 200yd zero?

2) Should the power setting remain the same thru-out the process of dialing my zeros at longer ranges?

3) What is the effect on MOA adjustments at various powers?

4) What other questions should I have asked?

I know this is basic. That's why I think its important to get it right. Believe me when I say thanks.

 

[Supermag]

Someone else please correct me if I'm wrong but, I would sight in with the highest power just so you can see the target better and shoot a better group (for POI reference). For everything else, it doesn't really matter about magnification or anything with concern to aiming/settings.

The magnification would matter if you were using a mildot or other ranging reticle or a point of aim different from the center of the cross hairs.

 

[eshell]

+1 SuperMag.

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1) What power should be used in sighting-in the rifle at a 200yd zero?

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With a good quality scope, point of impact will be the same, so it doesn't matter from taht aspect and higher magnification usually gives best results on targets. Mirage and other factors can make max magnification tough to use at times, so simply use the magnification level that you are most comfortable with, knowing your best precision will come with your best view.

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2) Should the power setting remain the same thru-out the process of dialing my zeros at longer ranges?

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No, not necessary unless you can prove your scope shifts zero with a magnification change, which is easily tested. Your Loopy shouldn't.

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3) What is the effect on MOA adjustments at various powers?

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It depends on your scope's internal design. Not sure how *your* 6.5-20 is set up, IIRC, it's a second focal plane scope.

If the scope has a "first focal plane" reticle, the reticle size will vary with magnification, as does the image, and you can use the same values for your reticle graduations throughout the magnification range.

If it's a "second focal plane" reticle (more common), the reticle will stay at a fixed size and the image will vary with magnification. In this case, one must always use the magnification setting indicated for ranging, usually the max magnification. Other magnifications will change the value of the reticle graduations and one will either have to compensate for this or disregard the graduations at that time.

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4) What other questions should I have asked?

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Good question. /ubbthreads/images/graemlins/wink.gif

 

[Stainless]

[ QUOTE ]
For everything else, it doesn't really matter about magnification or anything with concern to aiming/settings.

The magnification would matter if you were using a mildot or other ranging reticle or a point of aim different from the center of the cross hairs.

[/ QUOTE ]

Supermag,

Thanks for the response. Let's see if I've got it.

Basically, if I want to shoot a group at 100yds using 10x then shoot another group at 500yds using 15x, the change in magnification used at the different ranges makes no difference in applying my MOA calculations.

As long as I've dialed MOA correctly for each partiular range, the magnification can be whatever I'm comfortable using.

I dial it up for the range and wind, select the power of magnification, put the dot on the target, and then squeeze the trigger.

Do you guys agree these are the basic steps to be followed?

I'm not trying to minimize the skill and practice involved to accomplish this. I'm trying to understand the theory that I'm wanting to employ.

 

[Supermag]

You can shoot groups at whatever ranges with whatever magnification you want to use. I recommend the highest magnification you can use without mirage becoming a problem.

So yes, you are correct with a regular reticle the change in magnification shouldn't change the MOA calculations (unless the scope is broken or something).

 

[Stainless]

Thank you both for your replies. The project should be ready for the range in a week or so.