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zeroing in at 25 yards

147K views 44 replies 33 participants last post by  rojkoh 
#1 · (Edited by Moderator)
I have been told that when I sight my rifles (308 win and 30-06 sprfld.) in to dead on the bullseye at the 25-yard range that my rifles will be dead on at 100 yards. Is this a true statement? We were discussing how to sight in my rifles and not using so many rounds to do it. Then he said after the 100-yard sight-in is completed I could go up 6 to 8 clicks (1/4 @100 yards on the turrets) and be on target at 200 yards. What do y'all think about this..is he full of hogwash?
 
#2 · (Edited by Moderator)
It can be done with most calibers/chamberings but you have to know certain variables before you can complete the zeroing. You need to know the sight line axis above the barrel axis, the trajectory of the round you are working with, and then some fairly simple math calculations to determine the correct height. An easier way is to have your rifle zeroed at whatever range you want then place targets at the intervening range, shoot, and record the difference in height. Most can be roughly done using 1.5" below the point of aim at 25 yards, with a final check at 100 yards. It will be rough but get you on paper at 100 yards for final zeroing.

You definitely need to know your round's trajectory to make the 200-yard sight adjustment. There are tables that will tell you that information in many of the reloading manuals. Need bullet weight, ballistic coefficient of bullet, zero range, and bullet velocity at the muzzle. With that information look it up in various tables from the manuals.
 
#3 ·
There are other variables too. Scope above center height, velosity, bullet B.C.etc. You can can plug in these into a program such as the Hornady site and get a general idea. This will give you a good starting point, but always test in the field. I have tried this many times and I always must fine tune at the range 200 yd.,300yd.
 
#5 ·
A typically-scoped centerfire zeroed dead-on at 25 yards will shoot 2 to 3" or so high at 100 yards. This will put things dead-on again at somewhere around 225. There are many variables, however, the chief being the exact height of the sight line above the bore line. It is a useful rule of thumb to know for sighting a rifle as it can save you a lot of ammo (and frustration) just getting on the paper at 100 yards, but ALWAYS verify the zero at at least 100 yards before taking the rifle out to hunt.
 
#6 ·
Pisgah nailed it...zero at 25 yards with most modern centerfire rifles, of small to medium bore, and with a muzzle velocity of 2700fps, or more, and you'll be 2 to 3" high at 100 yards. Finish by dialing in at 100 or 200, or whatever range you prefer, but it's best to keep your groups around 3" high at 100.
 
#8 ·
pisgah hit it right on....now, there can be a problem and you should check your zero at 100 and then 200 yds, and maybe even farther. The deal is that if you don't hit EXACTLY where you are aiming, then that throws the whol trajectory table way off. If you are 1/2" off, man, you will be way off.
 
#10 ·
Excellent advice from many here. Dead center at 25 yards with most modern centerfire cartridges will indeed put you roughly 3" high at 100 yards. I've used this method for years.

I'd also like to suggest that you consider getting a book or two about rifles by Jack O'Connor. "The Complete Book of Rifles and Shotguns" and "The Hunting Rifle" are packed with excellent advice and information by a man who knew what he was talking about. The information is as valid today as it was when it was written many years ago. O'Connor's style will not bore you!

Go here: http://www.abebooks.com/

Type in "O'Connor" for author and "Rifle" for key word. You'll find both books for less than $10 each
 
#11 ·
Just a word about adding clicks for long range hunting shots -- I don't do it, ever. The reason is simple -- adjustment mechanisms are the primary things that can go wrong on any scope, even the highest-quality, most-expensive ones, and changing settings constantly is just asking for needless, accumulating wear. Except for situations where you're shooting at teeny-tiny targets at very long ranges (like plinking at 500-yard prairie dogs) it's just not needed. A mid-bore centerfire (think .30-06 or .270, say), zeroed 3" high at 100 yards, will plunk a bullet right in to the vtals of a hooved critter out to 400+ yards while you're still "holding on hair", as a friend of mine likes to say.
 
#13 ·
Everything depends on your expectations. Trajectory is either calculater or observed, but observation is always required. Ballistics programs are available (some free), or calculate yourself. For rifles, zero @25, is on the paper at no more than +3 @100, and if your target no more than 100 yards, & that meets your expectations, then go no further.

If not, then know your trajectories. If target shooting, exactness is important. If hunting, Point Blank Range (PBR) is important. PBR is decided by you, and is calculated based on the kill zone for your quarry. Example: kill zone for a moose might be 16 in. dia., but for a white tale deer it might be 8.

PBR has little relevance if 100 yds is tops, but if you might shoot at 150, 175, 200, ..., then its no longer just "nice to know". Ballistics programs reveal ball-park details, and range time refines it for your specific rifle & ammo.

In my case, I make trajectory printouts for each, and use them to know my capabilities. Follow-on range time gives confirmations, or reveals changes that must be understood & applied.

I enjoy my 7mmRM, .45-70, & 5.45x39. With a 4" PBR, my 5.45x39 has a max PBR of 248yds., dead-on @212, 6.5 low @300, -.25 @25yds, & +2 @100. If I shoot @300, then I'd better hold-over 2.5 in., or I miss the kill zone or lose the match. For my 7mmRM max PBR is 236, dead-on @202, -8 @300, 0 @25, & +2 @100. For my .45-70 max PBR is 131, dead-on @112, +.6 @25, +2 @75, +1 @100, & -11 @175. Note: All numbers change if I choose a different kill zone.

All of the above comply with zero @25, and no more than +3 @100, but there's a lot going on in between and after 100 that's critical to either target shooting or hunting.
 
#16 ·
Yup, that's the way we've always done it... after bore-sighting, make sure you're on or really close at 25yds and then that makes sure you're on the paper at 100yds for the actual zeroing. That way you don't start out at 100yds and miss the paper and have no idea which way to adjust it.
 
#17 ·
TMan,,you did'nt happen to have that planned out when you told the wife ''' we need a new window here ''' hahaha lol..neat idea even if you did'nt happen to get it that way..anyway ,thanks for the idea..just think man,,my wife is wanting a picture window put in..lol
 
#18 · (Edited)
Zeroing at 25 yards has two virtues: it saves ammo and it will get you "on paper" at 100 yards. Beyond that it is an unreliable measure of down range trajectory. I subscribe to the firm belief that you never know where the bullet will hit at any given range until you have shot it on paper, from hunting positions (not from benchrest) at that range. Computer generated trajectory tables are helpful but only in a general sense.

For the great majority of non-magnum, centerfire cartridges in scoped rifles from .243 through .35 caliber, sighting in 2" high at 100 yards will give a usable trajectory for hunting big game out to around 225 - 250 yards without hold over or hold under. Just take a manufacturer's table of factory ammo and study it. Sure, there will be some differences but how close can you hold your shots at 200+ yards? For most of us the human error beyond 150 yards is much greater than the half inch or so of trajectory difference.

Speaking as a Wyoming antelope, deer, and elk hunter (target games and varmints are a different matter), I keep all scoped centerfires sighted +2" at 100 (6.5X55, 280, '06, 35 Whelen, even .223) and all iron sight rifles zeroed at 100 (.30-30, 35 Rem., & .444). This gives me workable hunting and practice trajectories with all my long guns without remembering a bunch of different sight-in statistics for each one.

My scoped rifle rule: start at 25; refine to +2" @ 100; and always confirm longer trajectories by actually shooting at 200 yards. During hunting season if I can't get closer than approximately 200 yards I simply do not shoot. In the field, "always hold on hair."
 
#19 ·
Ballistics 101

For the newer among us -- the reason this works is that our sights are above the barrel and pointed at the target. The barrel is not parallel to the line of sight; it is pointed upward. The bullet starts out an inch or two below the line of sight and crosses through it some 25 to 35 yards out and continues to climb.

Gravity continues to work on the bullet and its climbing eventually slows and stops, and the bullet's path turns gradually downward, with the downward slope increasing as it gets farther and farther from the muzzle. The high point is referred to as the mid-range trajectory height and is listed in most ballistic tables. It will vary with the barrel's angle of elevation (determined by the range at which the rifle is sighted-in).

Sighting-in at 25 yards catches the bullet near where it crosses the line of sight on the way up, and it crosses it again on the way down at sight-in range.

The bullet's trajectory curve is gentler (flatter) with higher muzzle velocity, stretching the distance between the bullet's two crossings of the line of sight. A higher ballistic coefficient (indicating a more streamlined bullet) also makes the curve gentler.

Conversely, a blunt bullet makes the curve sharper, bringing the two crossing points closer together. A lower muzzle velocity also makes the curve sharper.

This covers Ballistics 101. For advanced courses, please refer to senior faculty members Uncle Nick and Humpy.

The Old Guy
 
#20 ·
I shoot for center of bullseye at 25 yards and expect to group 1 1/2" low and be right on at 100 yards. At 100 all I have to do is correct for windage. But that only works for one load. If I shoot 146 gr ammo the rules change since my usual load is 180 grains. Can't take Moe's assurance that it works for his Uncle Cletus and his best friend Fred. You need to get out there and put in the trigger time and find out what your load in your gun will shoot.
 
#21 ·
battlesight zero
is a 25 yard zero and the ballistic zero at range allowing for the lowest possible deviation in arc of flight to the terminus


battlesight zero for the 308 and the 30-06 are very similar - 0 to 250 yards
zero at 25 yards rezeros at between 235 and 250 yards depending on bullet weight and powder charge used

the path of the bullet never exceeds 4inches above or below the point of aim within that range
 
#22 ·
Welcome to Shooters Forum, LG101.

I did not realize the military had a designation for this well-known sight-in technique for rifles. I grew up knowing it as maximum point-blank range and learned it from the pages of books and articles written by Jack O'Connor, the champion of my much beloved 270 Winchester.

His recommendation to zero in at 25 yards sure has saved me a lot of frustration when trying to get on-paper at 100! :)

Hope to see more posts from you around the forum.
 
#24 ·
"battlesight zero" I like that! Thanks.

The whole concept of saving ammo is misleading. Most hunters need to shoot more than they do. If you have a good rest you should be able to boresight on paper at 100 yards and find zero in 3 shots. If you haven't shot enough to be able to do that then the "wasting ammo" is a must for you. :)

Here's a neat trick I saw..... write down your zero and other downrange bullet drops on the inside of your flip up scope cover. Put it upside down of course, so that when you flip it up, you can quickly check for any compensation you may have to employ. This helps if you shoot many different calibers and don't trust your memory anymore.
 
#25 ·
"battlesight zero" I like that! Thanks.

The whole concept of saving ammo is misleading. Most hunters need to shoot more than they do. If you have a good rest you should be able to boresight on paper at 100 yards and find zero in 3 shots. If you haven't shot enough to be able to do that then the "wasting ammo" is a must for you. :)
I remember the 25 yard sight-in from an ROTC Summer Camp at Fort Indiantown Gap in 1964 and the Army then called it a "battle-sight zero". I'd like to see you bore-sight an M1, a Remington 760, 7600, or side-lock muzzle-loader at 100 yards with 3 shots :D. The 25 yard zero is also useful for initial sighting when a scope has been replaced. Excess ammo used in sighting-in is wasted as it is not practice that will improve one's shooting from practical positions :p.
 
#27 ·
Sight it in at 25 yards. Then check at 100 yards, make corrections, then sight it in for the yardage you want. If you can't get to a range where this can be tested use the trajectory charts and approximate as best as possible then practice at whatever ranges you expect you might encounter.
 
#28 ·
I wouldn't sight in a new gun by truck headlights the night before opening day of deer season at 25 yards and then take it hunting the next day and expect it to be on at 100 yards.

But I recommend it to make sure you're on the paper before taking the target out to 100 yards.
 
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#29 ·
If you decide to get one, the best tool that I have found is the Sweeny Site-A-Line bore-sighter. Inside is an 'X'. Just center your cross-hairs on the center of the 'X' and you are good to go. Don't know if they are still being made, but if you find one for sale grab it - you will not be dis-appointed.
I have a Sweeny Site-A-Line, had it since 1969. They work great and save much ammo too! ;)
 
#31 ·
Close but not 'hunting close' if you get my drift. A check at 100 is imperative with the 17HMR. I used to have mine 1 inch high at 100 and that seemed to cover everything out to 150 plus a bit, which is all I needed. My CZ punched rough little holes about 1/4 inch diameter at 100 with five or more shots and the calibre is a surgical implement.
 
#32 ·
A new rifle and scope combination is shot 3 times at 25 yds after being bore sighted. I then proceed to shoot at a target 100 yds away, also shooting 3 more times. Then after checking my spotting scope I set the height of bullet strike according to where I am going to be hunting.;)

If I am going deer hunting in Missouri, it will be set to hit 1 inch high at 100yds.

If I am going to hunt elk or mule deer out in Colorado or Montanna, it will be set at 3.5 inches high at 100 yds. This will put me on the vitals at 300 yds easy.;) :D
 
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