Scope windage zeroing for long range

[Marksman63]

Fellows,
I need a quick check of my windage zero for a F Class 1000yds match.

Is a 50 yds zero safe enough or should I move to 100yds?

Cheers
Anleto

 

[CaptainMal]

That is a probably a "popcorn" topic, meaning you sit around and debate. Wind and mirage confound the issue so bad at 1,000 yards compared to short range the definitive answer is ..."maybe".

Most of my 1,000 yard experience is with a Dasher. Have seen 3-4 MOA (read more than a yard) at 1,000 from what I marked as a good windage start at 100 yards. Go back to my windage start and the next shoot, with environmental changes and I have to go the other way.

Then there's the unexplained. Won the 600 shoot last Saturday. Hard winds at 90 degrees to the range and I stayed near "on" the target while next to me a very experienced benchrest shooter had to hold off more than a foot using the same caliber. Think it was just a small change in bench position with the side berms changing the wind patterns for him.

I cannot make sense out of conditions at 1,000 compared to 100.

 

[Marksman63]

Agree, but what I mean zero is a scope calibration with no external factors, such as wind, mirage, etc.
Of course at shooting range things change, first of all adding spin drift correction, site angle, light conditions, altitude, etc. and wind parameters.
In theory my zero at zeroing range should be a zero at shooting range in abscence of external factors.

 

[Comrade Terry]

Is a 50 yds zero safe enough or should I move to 100yds?

I would zero the scope at 100 yards rather than 50 yards. Longer is better.

 

[Joe Salt]

Why do you guy complicate the crap out of getting on a 1000 yards? You only need to see the splash of the bullet on your first shot. I don't care what range 100, 200, or 1000 yards.
If you have a 100 yard zero that,s fine. I would worry more about elevation than wind. this is how you make it real easy, once you see the splash, don't care High, low. Put the cross hair or dot what ever, back on the bull. now click to the splash. Numbers don't mean squat to me. I've seen guys three targets over, clicked them to the splash, your in the money. I love guys sighting in there hunting rifles that burn up a box of shells or more sighting in.



Joe Salt

 

[skiutah02]

Scott and Joe have it right, IMHO.

I've shot at 1000 yds at 4+ ranges with 2+ rifles that I've zeroed at 100 and the cold bore shot was within 1MOA of POA. If you have a true, no-wind 100yd zero (remember even 1/4 in off will be compounded at 1000), and know the correct elevation for your bullet at 1000 you will be within 1MOA of the POA at 1000yds (if also in a no wind condition). The major drift (again assuming NO WIND) will be spin drift (about 1MOA) and scope misalignment from perfectly plumb.

So, perfect centered, 100yd no wind zero with correct elevation for 1000 will put you on target at 1000 within about 12" and the puller should see the impact on the berm. I'd rather see 100yd zero than 50yd since it is sometimes hard to distinguish 1/8" off center at 50yd then 1/4" off center at 100 which should have the same error at 1000.

Best to just go and shoot it.....

Drew

 

[Marksman63]

I would zero the scope at 100 yards rather than 50 yards. Longer is better.

Agree, but a 50yds rimfire range is available in 5 minutes drive from home and no cost for me.

 

[Comrade Terry]

Agree, but a 50yds rimfire range is available in 5 minutes drive from home and no cost for me.

Well, then - fifty yards it is!

 

[Mozella]

...... snip.............
In theory my zero at zeroing range should be a zero at shooting range in abscence of external factors.

By external factors, do you mean wind? If you zero your windage at 50 yards, assuming no wind, and then shot at 1000 yards, again assuming no wind, you can expect a lateral error of roughly .6 MOA. That's about 6 inches, which isn't much, but it's not zero.

Hint: Wind is not the only external factor and the actual lateral error depends on several things, some specific to your gun (twist rate for example) and some specific to the environment.

To see what the real number is for you gun, you need the help of a ballistics calculator. There are many on the internet for free.

 

[Marksman63]

By external factors, do you mean wind? If you zero your windage at 50 yards, assuming no wind, and then shot at 1000 yards, again assuming no wind, you can expect a lateral error of roughly .6 MOA. That's about 5 inches, which isn't much, but it's not zero.

Hint: Wind is not the only external factor and the actual lateral error depends on several things, some specific to your gun and some specific to the environment.

To see what the real number is for you gun, you need the help of a ballistics calculator. There are many on the internet for free.

Right, 0.6MOA drift is what my ballistics software say (Ballistics AE and Shooter)

 

[aussiepowderburner]

50 yards will be fine
A lot of scopes will not focus any closer
A perfect wind zero is critical in team shooting and is required for individual when you are having 180 degree wind changes!
Otherwise it will do your head in with wind / mirage values looking similar either side yet one side may require say 1.5 Moa hold and in reverse same value wind maybe 3.5 Moa if your wind zero is out by 1 Moa!
Any member with an incorrect wind zero really stuffs up the coach
Especially if in a dual coach full team environment

Even at 100 yards wind can factor into the equation
My opinion if outdoors the shorter distance is preferable
While at it make sure you are at 90 degrees to target as parralex can be a factor as well.
And if you plumb bob a line or use a level then draw a vertical line on target
Check wind zero - fire a shot at bottom of line ( use anything from 100 to 300 yard zero) - then wind on 20 Moa and fire a shot.
Wind back 20 Moa and fire another.
Good check to see if you have scope mounted properly ( if it is then you should cut the line above first impact ) and if scope is tracking as well!! Back to first impact at bottom?

 

[dragman]

unless your shooting on some kind of team, just get a zero your comfortable with and go with it. you will learn what kind of wind to call on your gun with how it is set up.