BDC Reticle and Magnification

[jmcd22]

I see conflicting information all over the place so finding an answer has been tough. Generally speaking, if you turn the power up on a BDC reticle, say from 6x to 10x at 200 yards, will this throw your zero off? To me, it doesn't make sense that it would move just turning the power up but I am far from an expert on optics.

Shooting a 7mm Mag with a Nikon Monarch 3 4x16x42 BDC if that helps.

 

[Formidilosus]

It will not effect the center crosshair. If you zero at 100 say, with the center crosshair, that crosshair will always be zeroed at 100 yards. All the other tick marks WILL change depending on what powers you are on.

 

[jmcd22]

Odd. I was shooting out of a sled and as I turned the magnification from 6x to 8x to 10x, my groups were all over the place. Groupings themselves were good but the group as a whole had no consistency. Back to the drawing board I guess.

 

[Formidilosus]

I was shooting out of a sled

That. Stop using a lead sled. They are the biggest causes of stupid stuff with rifles in modern history. Not to mention, the zero isn’t the same between sled and no sled.

 

[AZ_Hunter_2000]

No change to your zero. Depending on if your scope is first or second focal plane, the yardage associated with the hashmarks will change. First: no change, Second: change.

Sleds are not necessarily the best method to test accuracy. Try using a bipod and a rear rest to see if that will improve the consistency.

 

[Fatcamp]

My Nikon Monarch was not consistent. At all.

 

[Mike Islander]

Theoretically your zero will be the same regardless of magnification. This is whether your scope if first or second focal plane. For second focal plane scopes (which most of us use) your yardage for each BDC ball will change, with the difference in yards between each ball going down as you increase the magnification.

For example, my Monarch 3 2.5-10x42 sighted in at 100 yards is basically 200, 300, 400, 500 and 600 yards (206, 306, 392, 517, and 625 on the top of the post) centered on the balls beneath the crosshairs...at 10X (and pretty close to that at 9X out to 400 yards). But at 3X with the exact same load the balls are 382, 625, 822, 1068 and 1262 yards.

These numbers change with load (bullet speed and BC).

 

[roadrunner]

When using the BDC marks, I always use max magnification, for a reason. The target is a long ways off. Unless the zero is at 25 yds, having the scope dialed down doesn't make sense.

If zeroed at 200, shots under won't need drop compensation and dialing down helps considerably when you accidentally up on a bedded 200" buck in his bed in thick cover.