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Is a 25-Yard Zero Dead-On at 100 yards?

By Keith Wood (RSS)

June 10, 2011

By Keith Wood

The Myth: A 25-yard zero puts you “dead-on” at 100 yards. I’ve listened to some pretty amazing ballistic theories over the years but this one is probably the most common. The theory is that, with common big game cartridges, a “zero” at 25 yards will correlate to a second “zero” at 100 yards.

The Ballistic Background: First we have to understand the concept of zero.  Because a rifle’s sights are not inside the bore and a bullet’s flight path is subject to gravity, we must align our sight to intersect with the bullet’s path at a given distance.  Generally, we consider the rifle’s “zero” to be the point at which the bullet’s path intersects the line of sight for the second time.  In other words, if the bullet strikes the line of sight at 25 yards and then rises relative to the line of sight before falling and intersecting the line of sight again at 100 yards, we have a 100 yard zero. 

chart

Let’s look at a few common examples:

.30-06 Federal Premium 165gr. Nosler Partition 2830 fps (Factory)
25 yard zero=2.77 inches high at 100 yards

.270 WCF Winchester Silvertip 130gr. 3060 fps (Factory)
25 yard zero=3.0 inches high at 100 yards

.243 Winchester 100gr Hornady Interlock 2960 fps (Factory)
25 yard zero=2.9 inches high at 100 yards

Fact is, most common big game loads would be about 3 inches high at 100 yards. For hunting purposes it may be "close enough," but it's not "dead on" for most calibers.

The Conclusion: A 25-yard zero will put your bullet around 2.5 to 3 inches high at 100 yards depending on caliber, but it's not "dead on."

Tags:  25-yard zero,  american hunter magazine,  blogs,  bullshooters,  bullshooters column,  jeff johnston,  keith wood

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16 Responses to Is a 25-Yard Zero Dead-On at 100 yards?

Whoofbang wrote:
January 19, 2013

Thr 25 yd and 100 yd zero works with black powder and pistol cartridges, 44 mag, 45-70, 38-55, 357 mag, are a few. It depends on the initial muzzle velocity.

JustMe wrote:
November 20, 2012

For a 30-06 remington cor-lok 180gr a 200 yd zero gives a 25 yd zero(actually 0.1in under), and 308 cor-cok is an inch high at 25yd for a 200yd zero. So not true for 100yd but close for 200yd.

JUSTIC CHAVIS wrote:
September 08, 2012

does a full metal jacket or blistic tip make any difference???

Joe Locklear wrote:
February 06, 2012

I want to shoot hogs with my Marlin 336 in 35 rem. with a Trijicon 1-4 scope. I would not expect to take a shot past 100 yards. If I zero at 25yards, where should I be on paper for the closest to average zero from 20 to 100 yards?

GS wrote:
November 29, 2011

The purpose of 25 yard zero is not to be dead on at 100 yards but instead to achieve the maximum point blank range of the cartridge. MPBR would normally be up to 3" high at it's highest and 3" low at it's lowest with no need to "hold over" as your chart clearly shows 275 yards for the 30.06. 3" high or low behind the shoulder will still kill a deer.

culring nut wrote:
November 09, 2011

I heard if I can only sight in at 25 yards if I hit the target 1/4" low of center, then at 100 yards I'll be close to right on?

Raff wrote:
July 27, 2011

I sighted a 7mm Rem Mag at 25yds., impact was : 1/2" high at 50yds., 1" high at100yds.,4" high at190yds., dead on at 265yds. (140gr. BallisticTip@3475fps)

KW wrote:
June 17, 2011

Phil, you make a good point which reenforces the theme of the blog: that nothing is ever absolute. "Rules" like these are rarely accurate due to the endless number of variables involved.

Phil wrote:
June 16, 2011

Your figures are based on the line of sight being 1.5" above the center of the bore. It doesn't have to be very different to get significantly different results.

Casual Shooter wrote:
June 16, 2011

@ Richard. No, the .308 round has ballistics very similar to the .30'06. When zeroed at 25 yards, it will also shoot 2+ inches high at 100 yds. The same with the .223. Possibly the .22LR is anemic enough to zero at both 25 yds and 100 yds. But what you're saying is certainly not a fact.

Rich wrote:
June 16, 2011

Over in 'Nam, we had 25 meter ranges outside the wire of our fire support bases. SOP with the Big Red One was zero your 16, always have fresh ammo, it'll keep you alive.

Herman wrote:
June 11, 2011

A 25yd zero on a 30-06 will allow you to kill a deer from 1 to 300yds, your bullet will always be in the killing zone.

Rob Felcher wrote:
June 11, 2011

Always heard this, good to see some real facts.

Jipple wrote:
June 11, 2011

Makes total sense. Good analysis.

Bill Kappele wrote:
June 10, 2011

It seems that people mistake Maximum Point Blank Range (MPBR) sighting for Dead On sighting. Sighting at 25 yards can be useful for MPBR sighting.

Richard wrote:
June 10, 2011

That myth comes from the fact that a 25 yd zero will be a 100 yd zero for the 5.45/.223 & 7.62/.308 rounds. Depending upon temperature and altitude of course.

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