Magnification setting and accuracy (Swaro Z5)

[Bill in MI]

1st time poster here, so thx for all advise and comments

Background:

I just upgraded from a Nikon Monarch 3x9 to a Swaro Z5 3.5-18x44 BRX.

This is to be mounted on a tried and true 9 year old custom Win M70 300WSM shooting Nosler custom loaded 180g Accubonds.

I am not a true long range shooter but will get to practice out to 400 yards.

Questions:

Can you explain why the reticle is only 'accurate' at a set magnification?
Do you have to be set on 18x even for close range shots under 200 yards?
If I were to shoot at 10x for instance, what deviation would there be at 100 yards, 200 yard etc?

Thx for helping with some basics here.

Bill

 

[Mikecr]

The BRX is a hold-over reticle, where the various stadia correspond to some distance (moa or mil). regardless of merchandising, they are only as accurate at ANY power setting as you have tested locally.

The main cross hair(what you aim with up close if you don't dial) is not dependent on the power setting.

 

[bruce_ventura]

The BRX/BRH reticle has a spacing of 1 mrad between dots at max magnification (18X for your scope). Reduce the magnification to half that value (9X) and the spacing between dots will be 2 mrad.

 

[Crews]

In layman's terms..... when they say it's not accurate unless it's at a certain magnification, they're talking about the spacing on the reticle used for ranging estimates and holdovers. The center of the crosshairs are in the same place no matter what power you have it set on.

 

[Laelkhunter]

You should sight in dead on @ 200 yds. This will put you a little high @ 100. Go on the Swarovski Ballistic program and enter your bullet info, and it will tell you where the point of impact will be for each stadia line, however 200 will be your zero. It lists numerous factory loads, but if you are going to reload, you can enter the info, but you need to know bullet BC, and muzzle velocity.
There are many variants that can cause changes in bullet point of impact (temp, humidity, altitude, etc), so they are just giving you an estimate. You should shoot the rifle at different ranges to see where the actual bullet impact will be.
At less than 200 yards you will be in the "point blank"range, meaning the bullet should not be too high or low to matter. You can use any magnification, it shouldn't matter. Just aim where you want to hit, and it will be within an inch or so of where you are aiming.