Scope zeroing question

[Ragnar Danneskjold]

I have a Konus M30 6.5-25x Mil-Dot rifle scope and I am reading up on precision rifle shooting. I know that the scope has horizontal lines that show how many times the turret knob has been rotated. My question is, when zeroing the rifle at 100yds, which line should I lock the knob at for the zero? Should I zero the knob at the lowest rotation marker? Or should I perhaps set it at 1 or 2 rotations to give it space to go the other way?

Same question for the windage knob. It has 8 rotation markings, vertical in this case, that denote how many times the knob has been turned. Should I leave it at the lowest setting, or perhaps set it to say, the 4th line, which would split the difference and allow 4 rotations either way.

 

[dakotasin]

you're going to have to let the rifle dictate most of that.

if you want to put the effort and time into it, a scope will be on its best behavior when the reticle is centered - meaning the exact same number of clicks from up/down, left/right.

that really isn't practical for most folks.

if you are using std bases, sight the gun in using the screws on the rear base to adjust for windage while your reticle is centered, and turn your turret for elevation. that is the easiest practical way to have your scope's reticle centered.

to directly answer your question, you should count clicks from stop to stop, then turn back half as many for both your knobs - that will center your scope and you're windage should be at 4-0... likewise your elevation (probably won't be, but that's another discussion).

 

[ms6852]

I do not know much about the Konus scope but there is a lot of information you are not divulging about the scope. Such as is it 1/4 moa per click or 1/8 per click? How much internal adjustment is there on the scope for elevation. For example it the scope has 60 moa of total internal adjustment than it has 30 moa of up adjustment and 30 moa of down adjustment. That means that at 1/4 moa that would mean 120 clicks of up or down adjustment. Your manual should also indicate how much one full revolution of the elevation knob will equal in moa. For example starting at zero and turning in the direction of the "UP" arrow and stopping at zero again some scopes may give you 10 moa total or 40 clicks at 1/4 " moa. Than the one line you see at the bottom of the scope would indicate 10 moa, 2 lines would indicate 20 moa and so forth.

 

[Ragnar Danneskjold]

It has 1/8th MOA turrets. I counted 630 clicks from one side to the other for elevation, so divided by 8 that's 78.75 MOA. It is 48 clicks per rotation, so 6 MOA. Since that's an odd number of total clicks, would I be able to round that to 624, thus making 13 turns of 48 clicks each?

And then onto my question. When the rifle is zeroed at 100yds, how may rotation markers should it be set at? Should I return it to the midpoint, being marker 7?

 

[Ragnar Danneskjold]

Wait, I think I just figured a few things out. So since I have 624 total clicks, the half way point, or factory zero is 312. Which is 6.5 rotations. So would I bring the turret up from the bottom max 6.5 rotations, reset the turret to 0 there, and then that's my factory zero? And then any time I make a 100yd zero for a certain temperature, I notate how many clicks away from that factory zero the 100yd zero is, so I can recreate it later?

 

[dakotasin]

you're on the right track but... your 'factory' zero may not be anywhere close to your rifle's zero.

sight the rifle in for 100 yards, set your turrets up for that zero, and you have your baseline. if you are not happy w/ how far off the scope is from what you call a 'factory' zero to the actual zero, you will have to work with angled bases or rings to get the rifle there.

 

[Ragnar Danneskjold]

But isn't my 100 yd zero going to change based on conditions like temp? I have a zero summary chart in my book where I can input what my zero is for a wide range of temperatures and ranges. So say tomorrow is going to be 70deg Fahrenheit, and my 100yd zero is 50 clicks up from the 312 factory midpoint. Would I write down in the 70degree/100yd space "+50", so that if I shoot on another 70 degree day, I can just movie the turret up from the midpoint 50 clicks again and be pretty darn close? And also lets say I shoot on an 85 degree day later on. So for that day I zero and it's only 40 clicks up from the 312 midpoint, I would then notate that in the 85degree/100yd space "+40"? And of course likewise if I shoot on a 42 degree day and I gotta bring it down from the midpoint, etc.

Am I on the right track with any of this?

*I'm pulling those numbers out of my rear just for the example. Also since I am practicing military/LE style precision shooting, and not hunting, would I be right about the 100yd zero changing since I am going to practice in a wide variety of temperatures and ranges?

 

[dakotasin]

yes, environmental conditions can/will affect your zero, but the impact at 100 yards will be so minimal you may not ever see it. you will notice it at much longer ranges. for 100 yards, most rifles can 'set it and forget it'.

also, we are making a few assumptions here that may not be true. we are assuming that your rifle is accurate enough, that the way you hold the rifle doesn't change, and that your scope tracks perfectly. all three of those factors will have a bigger effect on your 100 yard zero than environmental conditions.

try this: go zero your rifle on the bench with sandbags at 100 yards. then, sling into your rifle and shoot a few groups from prone. then, re-sling and shoot from seated. last, shoot offhand. your groups' poi is likely to change pretty significantly from your benched and bagged zero. or, do the same routine from a bipod. again, your poi's will probably be different. you need to minimize those differences before you can start blaming or fixing the scope and mounting system.

you are on the right track, but the first thing to do is get the rifle itself sorted out. after the rifle, you have to sort the shooter out.

 

[mdThanatos]

Are the knobs resettable? If they are, go zero in everything and then reset the knobs then you can adjust for either up/down or left/right based on distance and what not.

 

[Uncle Mike]

environmental conditions can/will affect your zero,

What dakotasin is saying is right on the money. Set your 'zero' as close to 'center' in the scope tube or as close to it as can be achieved as to the rifles actual zero, this is your 'base zero' for a given set of atmospheric conditions, and that should be conditions you anticipate shooting in the most.

As conditions change you change your settings BUT, you know were base zero is at, so you can return to that later.

Also keep in mind your 'cold bore' shots will usually be off from the rest of the shots taken at any one particular time, so you'll have to make a note of that, and adjust from base zero for that first shot...IF your going to be that anal about your shooting, it really only applies to longer range shooting.

There are many different ways to 'zero' a reticle, you may want the junction of the stadia to be base zero, or you might want the upper most dot in a mil dot scope to be that base zero, whatever...the junction of the stadia wires is the most popular.

Your definitely on the right track with the note taking... once you 'base zero' your scope, you adjust from that point for any changes in atmosphere, range or wind, noting everything! And then, when the excitement is over, you simply resort back to your 'base zero' and happy happy joy joy!

Also, use a 'no wind' condition to base zero.