Zeroing

jwh525

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I've got a question and I'm sure I'll probably get various answers. At what range do you zero your rifle? I've typically zeroed at 100 or 50 yards. The 100 yard zero made adjustments so easy. The problem is that around 250 yards there is a drop of 5 1/2" and at 300 it has a 9 1/2" drop. When we zeroed in the military we did so at 25 meters. Is there truly one magic zero range? The caliber that I'm getting my data from is a 270WSM
 

elkantlers

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I usually zero at 200yds. That way it is a dead on hold out to 300+ yards depending on the caliber. You will be a couple inches high at 100 and a few inches low at 300+.

Most shots should be in this range with a little effort.
 

npaden

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I would guess the most common zero for a lot of western big game hunters is 2" high at 100 yards.

That will get you about dead on at 200 yards for most flat shooting rifles and a little low at 250 to 300 yards.

What grain bullet are you shooting for that big of drop on a 270 WSM? I thought they were pretty flat shooting.
 

jwh525

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The bullet was a 150 grain BT.
The data from the app was this:
25 yard zero
50yds - rise of 1.24
100yds - rise of 3.10
150 yds rise 3.94
200yds rise 3.71
250 yds rise 2.32
300ds drop .39
I have not verified this since I don't have access to any range longer than 100.
 

sbhooper

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Bullets do not rise after they leave the barrel. They start straight and then start dropping. You are talking about inches above or below the line of sight. It is impossible for bullets to rise, due a small issue called gravity.

I know the exact velocity of my bullets and their BC. I start with a sight-in at 100 yards to make sure everything is on. I then move to 200 and zero at 200. I can then take that data and determine pretty well where they will hit as far out as I care to shoot, by entering the data in the G-7 ballistics calculator.

A couple of my scopes have ranging ability with either dots or lines. Shoot each line at your sight-in range and then measure each hole's distance above the zero. That data can then be figured out using the calculator as to what range each line will be a dead hold. It has proven to work well out to my 600 yard max.

If range is limited, use a 100 yard sight-in. Adjust the impact point to be as far above the target hold as is necessary to hit the dead-on range that you desire. Knowing your ballistics is a must for exact sighting, if you are going to do any long-distance stuff.
 
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fishing4sanity

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For big game hunting in the west 200 yds seems to be very common for zeroing a rifle. I have my hunting rifles zeroed at 200 typically and range/competition rifles at 100 yards.
 

BuzzH

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I've used either a 250 or 300 yard zero for the past 15 years or so.

In the last 10 or so, I've switched to 250 and then spin turrets from there.

Just be aware that when your zero is much beyond 200 you have to be mindful of the bullets highest point above zero and where that is. Its pretty easy to shoot over things in that 130-160 yard range if you don't.

IMO, unless you shoot a bit and understand the LOS/zero fairly well, I would stick with a 100 or 200 yard zero.

Good luck.
 

JLS

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Follow Buzz's advice. It would be a bummer to miss a critter at 100 because your gun is hitting 6-8" high in order to achieve a 300 yard zero.

I go about 2.5 inches high at 100
 

RobertR

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I will stick with the 27 or 100 yard zero because in close quarters in the timber 30 yards or less it only takes one branch to make you miss or wound an animal. I can still bracket an animal with the duplex for longer shots.
 

jwh525

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Thanks for all of the input. I was wrong on the original posting. The drop was for a 338 not a 270WSM. I'm headed out to Idaho this fall for an elk hunt and was curious as to my sight in distance.
 

Gut Shot

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In the military you zeroed at 25 meters because the bullet crossed line of sight there and fell back into line of sight at 100 meters. Therefore the 25 meter zero would also equate to a 100 meter zero (approximately).

This picture shows lines of sight and trajectory.
ballistics.jpg



I usually zero 2" high at 100, then shoot at 200 and 300 to verify everything.
 

Gunner46

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It's simple to 'Zero' at what ever range you desire, even shooting at a 100 yd range. I don't advise a 25yd sight in for any rifle, because just a fraction of an inch variation translates into many, many inches as the range increases..

There are dozens of on-line calculators that will let you play with trajectories, PBR's, etc, to your hearts content.

I like this one. http://www.shooterscalculator.com/

2" high at 100yds, is a longtime Go-To guideline.......Cuz It Works !
 
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MinnesotaHunter

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In the military you zeroed at 25 meters because the bullet crossed line of sight there and fell back into line of sight at 100 meters. Therefore the 25 meter zero would also equate to a 100 meter zero (approximately).

This picture shows lines of sight and trajectory.
ballistics.jpg



I usually zero 2" high at 100, then shoot at 200 and 300 to verify everything.

This is inaccurate. The military zeros at 25m (Army) or 36m (Marines), because they are concerned about quanitity versus quality when it comes to zeroing. IE: we need to get 200 people zeroed this morning, so a 25/36m is good enough. Where most people can logically understand that a 100m zero will be more precise than 25/36m. Some specific units will buck the standard and do 100m zeros, especially for Soldiers equipped with a more advanced optic than the standard iron or aimpoint.

As for the equivalence of the expedient zeros. 25m equals a 250 or 275m zero (depending on the version M16A1, M16A2, M4A1, BUIS). the Marine 36m zero is equivalent to a 300m zero.
 

Gut Shot

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This is inaccurate. The military zeros at 25m (Army) or 36m (Marines), because they are concerned about quanitity versus quality when it comes to zeroing. IE: we need to get 200 people zeroed this morning, so a 25/36m is good enough. Where most people can logically understand that a 100m zero will be more precise than 25/36m. Some specific units will buck the standard and do 100m zeros, especially for Soldiers equipped with a more advanced optic than the standard iron or aimpoint.

As for the equivalence of the expedient zeros. 25m equals a 250 or 275m zero (depending on the version M16A1, M16A2, M4A1, BUIS). the Marine 36m zero is equivalent to a 300m zero.


Give me a break, I haven't been in the military for about 20 years now.:D
 

HighDesertSage

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I don't really know what my "zero" distance is, but I bet is over 300. I sight in 3" high at 100. 0-350 I hold center of chest cavity. 400 I hold the horizontal crosshairs on the top of the back. 400+ I get closer. This method has served me well for and works great when shots happen fast. I think a 270 WSM would be similar to a 150 grain bullet out of a 300 win.
 
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HighDesertSage

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I pulled this off of federals ballistic calc site:


BALLISTICS CALCULATOR

Load Number: P270WSMTT1 Zero Range: 310 yd
Caliber: 270 Win. Short Magnum Temperature: 45 °F
Bullet Style: Trophy Bonded® Tip Wind Speed: 10 mph
Bullet Weight: 130 gr Altitude: 6500 feet
Ballistic Coeffcient: 0.44 Max Range: 500 yd
Muzzle Velocity: 3280 fps Test Barrel: 24 in
Sight Height: 1.5 in


Range (yd) Drop (in) Wind Drift (in) Velocity (fps) Energy (ft-lb)
0 -1.5 0.0 3280 3105
50 1.2 0.1 3186 2929
100 3.0 0.5 3093 2762
150 3.9 1.1 3003 2603
200 3.8 1.9 2914 2452
250 2.8 3.1 2828 2308
300 0.6 4.6 2743 2171
350 -2.8 6.3 2659 2041
400 -7.3 8.3 2577 1917
450 -13.2 10.7 2497 1800
500 -20.3 13.3 2418 1687
 

sagebrush

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Not sure where you came up with the 4 inch different between 250 and 300 yards. Your app data shows only a 2.61" difference. Sounds like 3.10 high at 100 would give you a pretty good point blank range, 4" high at 150 and 4" low at 400. That's just an 8" kill zone when you hold dead on from 0 to 400 yards, small enough for any deer.

I would use the G7 calculator for your load data and then verify at 50 and 100 yards at the range. You can enter in your actual results into the G7 calculator and it will adjust the drop data accordingly. Print out a drop chart in 25 yard increments until your ft-lb drops below 1200 and that's your max range for elk and 1000 for your max range at deer.You then should be good to go.

I think it goes without saying, if you can only practice at 100 yards, I would limit my shots on game to 300 yards maximum and that's only if you can clover leaf a three shot group every time at 100 yards.
 
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RobG

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In the military you zeroed at 25 meters because the bullet crossed line of sight there and fell back into line of sight at 100 meters. Therefore the 25 meter zero would also equate to a 100 meter zero (approximately).

This picture shows lines of sight and trajectory.
ballistics.jpg



I usually zero 2" high at 100, then shoot at 200 and 300 to verify everything.

Just for the record to avoid confusion, the first time you said it results in a 100 yd zero, but I think you meant 200yd.

I was taught the 25 yd rule, but it seems like the second zero point would vary a lot depending on ammo and caliber. As a practical matter how much variation can you expect?
 
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