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Thread: Jack O'Connor's 25-yard sight in?

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    Member Forager's Avatar
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    Default Jack O'Connor's 25-yard sight in?

    Hi folks.

    Just read something in which Jack O'Connor recommended sighting in at 25 yards, suggesting that typically (eg, .30-06, 180 grain, let's say...) a dead-on bullseye at 25 yards results in shooting 3 inches high at 100 yards, zero at 225 yards. Unless I misunderstood, which is quite possible.

    (He also said that if he could only have one all-around rifle it would be a .375 H&H, if he could have two it would be a .375 and a .270.)

    I've always zeroed at roughly 2 inches high at 100 yards (depending on caliber/bullet weight/etc.), only using the 25 yard demarcation as a starting point to make sure I'm on paper in the vicinity of the target. But this is kind of an intriguing idea...

    Wondering if anyone has ever done this (zeroed only dead on at 25)? Also, anyone with better background in ballistics than I have care to comment on the viability of this?

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    Supporting Member Amigo Will's Avatar
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    I sight in at 25 or 50 yards with no problem so far
    Now left only to be a turd in the forrest and the circle will be complete.Use me as I have used you

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    Member GrassLakeRon's Avatar
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    I sight in at 25 as well for factory. 23 for my handloads.

    one day closer to alaska.
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    Quote Originally Posted by Amigo Will View Post
    I sight in at 25 or 50 yards with no problem so far
    Dead on at 25, resulting in a 200 or 225 yard zero?

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    Member Daveintheburbs's Avatar
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    I start by sighting in at 25 then adjust at 100. Minor deviations at 25 are obviously multiplied down range. The good news is that you can get very close before all that work down range. If you can approximate your load or better you know your velocity and BC this tool is a lot of fun to mess with:

    http://norma.goldbergsoftware.se/?lang=en&?v=2

    BTW Norma claims their 180g 30-06 dead on at 25 = 2.56 high at 100, dead on at 200.

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    Starting out at 25 yards after bore sighting is a practical way to start to zero a rifle scope in. I zero my center fire rifle scopes to hit dead on at 200 yards as most Alaskan game is shot under that range and I don't worry about hold over from the muzzle to a little over 200 yards. I want the bullet to land close to where the scopes reticle is placed on the target.

    I have heard about the "maximum point blank range" sight in for many years. I will stick with what I am doing. If I ever got into hunting where my first shot at a critter was consistently over 300 yards I would get something else besides my 30-06 and .338 Win. Mag.

    I never want to mentally calculate whether my shot is going to land high when my scopes reticle is pointed at a critters vitals. I would much rather use hold over if I think a critter is close or over 300 yards, as it is all I have done in the last 50 years and I am used to it.

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    Default JOC is/was right

    Somewhere I have a copy of a reprint of a JOC article, that was included in the package with Weaver Scopes.

    IIRC, JOC recommended sighting in 3 inches high at 100 yards. Initial sighting was done at 25 yards.

    The actual distance the rifle is sighted in for, depends on the ballistics of the particular cartridge and load.

    The article included a chart with trajectories of popular cartridges.

    In a pinch, 25 yards for a scoped rifle is a good, but to refine it to 3" high at 100, is better, and to sight in for actual distance, you choose for maximum Point Blank Range is better than that.

    For a scoped rifle, tis said the bullet will cross the line of sight the first time at bout 25 yards.

    I suggest you use a trajectory program you can find at various websites, to answer your question.

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    Scope height over the bore will have some effect on that. With taller mounts for big-belled scopes make me sight in about an inch low at 25 for similar results. He's pretty much right on for standard height rings, but for low rings I like to be a little above dead on at 25. Open sights cobble those numbers all to heck, but there's still a relationship between sight height and how high you want to be hitting at 25.

    But in truth that's only to get me "on the paper" at 100 yards. I still go ahead and shoot at 100 and 200, and with flat shooters at 300 and 400 too. And there's nothing sacred about 3 high at 100 when it comes to the flat shooters. I keep my 7mm RemMag 4 high at 100, which puts it 5 high at 200, a little over an inch high at 300, dead on at about 325 and 4-5 low at 400. Good enough for holding dead on for lungs all the way out to 400 and no figuring.

    One thing to do for sure after going out and shooting further: Come back in to 25 yards and shoot it again to see where it is hitting. File that number somewhere so you can find it again, so if you ever doubt your sight-in while in the field, or if you know the gun got knocked around, you can do a 25 yard shoot once again to confirm or deny changes.
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    Quote Originally Posted by .338 mag. View Post
    Starting out at 25 yards after bore sighting is a practical way to start to zero a rifle scope in. I zero my center fire rifle scopes to hit dead on at 200 yards as most Alaskan game is shot under that range and I don't worry about hold over from the muzzle to a little over 200 yards. I want the bullet to land close to where the scopes reticle is placed on the target.

    I have heard about the "maximum point blank range" sight in for many years. I will stick with what I am doing. If I ever got into hunting where my first shot at a critter was consistently over 300 yards I would get something else besides my 30-06 and .338 Win. Mag.

    I never want to mentally calculate whether my shot is going to land high when my scopes reticle is pointed at a critters vitals. I would much rather use hold over if I think a critter is close or over 300 yards, as it is all I have done in the last 50 years and I am used to it.
    Methinks, that makes a lot of practical sense.

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    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

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    Quote Originally Posted by BrownBear View Post

    One thing to do for sure after going out and shooting further: Come back in to 25 yards and shoot it again to see where it is hitting. File that number somewhere so you can find it again, so if you ever doubt your sight-in while in the field, or if you know the gun got knocked around, you can do a 25 yard shoot once again to confirm or deny changes.
    I need to do that.

    SOTN
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

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    Supporting Member Amigo Will's Avatar
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    Windage needs to be nutts on at 25.
    Now left only to be a turd in the forrest and the circle will be complete.Use me as I have used you

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    Quote Originally Posted by Amigo Will View Post
    Windage needs to be nutts on at 25.
    I have sighted several rifles in at the last minute on Friday night at a guessed 25 yards and then killed coyotes all day Saturday and Sunday with same. I usually draw intersecting vertical and horizontal lines on paper an shoot at the intersection of the lines. I prefer to be a quarter to half inch low but more important the vertical line must slice the bullet hole equally in half.

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    Supporting Member Amigo Will's Avatar
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    In Viet Nam you showed up to a outfit and were issued a rifle. Our sight in pit was about fifteen yards. With this sight in pit I have seen VC hit at 400 yards with the m-14. Don't know if any military carry their weapons from stateside to battleground now days.
    Now left only to be a turd in the forrest and the circle will be complete.Use me as I have used you

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    I only shoot a rifle at 25 yards if I can't bore sight it first. I only take one shot, and then calculate the number of clicks right or left and up or down, to get it to the bull at 100 yards. Usually I shoot one time at 100 yards after bore sighting ( so it's on paper at 100 yards) and the calculate then clicks to be on at 100 yards. Then I calculate clicks one more time to get my rifles to shoot approx. 1.2 inches high at 100 yards (it varies a little between cartridges/loads) and shoot a three shot group. If I'm "on", Then I go to 200 or 300 depending on the cartridge to double check. This gives me a 150 yard zero. I like a 150 yard zero because it doesn't matter if I'm over 7" or 10" or whatever at 300 yards. I figure if I'm shooting 300 yards or more....#1 I better now the yardage + or - within 10 yards or so...#2 I better have time to figure hold over (If I don't have time, I'm not shooting). This next part is the most important to me. When I'm in the woods and I have a shot at 75 to 150 yards and I only have a softball size hole in the saplings, branches, and twigs, I don't want to be screwing around with numbers in my head figuring if I have to shoot a little low to get that bullet though the that hole. These closer shots are my bread and butter shots, I can get them off pretty quick if I have too. So why hinder the usual shots with 3 or 4" high at 100?

  15. #15

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    That's approximately the strategy I use with my rifles mounting receiver sights, specifics adjusted for caliber. They're mostly used inside 200 yards, while in open country my scoped rifles may expected to draw down on game to 400.

    My Savage 99 in 358 is sighted in a couple inches high at 100, more or less right on at 200. My Winchester 71 in 450 Alaskan has a virtually identical trajectory as the 458 Winchester, so I sight it in dead on at 100, putting it about 4 low at 150. My Marlin 336 in 35 Remington has the same sight in, as does my Marlin 95 in 44 Kodiak (a .429 wildcat based on the 45-70 and launching 300 grain slugs at 2250).
    "Lay in the weeds and wait, and when you get your chance to say something, say something good."
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    Quote Originally Posted by Amigo Will View Post
    In Viet Nam you showed up to a outfit and were issued a rifle. Our sight in pit was about fifteen yards. With this sight in pit I have seen VC hit at 400 yards with the m-14. Don't know if any military carry their weapons from stateside to battleground now days.
    yes when we deploy we take our rifles with us..

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    Member Armymark's Avatar
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    Quote Originally Posted by Forager View Post
    Hi folks.

    Just read something in which Jack O'Connor recommended sighting in at 25 yards, suggesting that typically (eg, .30-06, 180 grain, let's say...) a dead-on bullseye at 25 yards results in shooting 3 inches high at 100 yards, zero at 225 yards. Unless I misunderstood, which is quite possible.

    (He also said that if he could only have one all-around rifle it would be a .375 H&H, if he could have two it would be a .375 and a .270.)

    I've always zeroed at roughly 2 inches high at 100 yards (depending on caliber/bullet weight/etc.), only using the 25 yard demarcation as a starting point to make sure I'm on paper in the vicinity of the target. But this is kind of an intriguing idea...

    Wondering if anyone has ever done this (zeroed only dead on at 25)? Also, anyone with better background in ballistics than I have care to comment on the viability of this?
    The US Army zeros at 25 meters and the rifle is dead on at 300 meter with the M4 and was the same with the M16. Assuming Joe Joe has a legit shot group. On the KD range good shot groups from this zero are about a 5 inch group at 300 meters center mass. Sight height and velocity with different cartridges will have a play but usually it will be good enough for big game out to 300.

    Mark

  18. #18

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    Quote Originally Posted by Armymark View Post
    ...Sight height....
    Glad to hear you say that. Most guys don't have a clue about it. Even with the low vels of my traditional muzzleloaders, the difference between original guns with sights only 1/8" high and the 1/2" on modern sights has a huge impact on downrange POI with close range sight-ins.

    You'll see it too, when comparing high sights on an M16 for example with the low sights of most bolt guns. Heck, you can even see it when moving from low rings to high rings on scopes.
    "Lay in the weeds and wait, and when you get your chance to say something, say something good."
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    Member Armymark's Avatar
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    O'Conner's method and a version adopted by the Army is a time control method. It sacrifices a little accuracy in poi for a whole lot of time. It reduces the range distance requirement to meet an acceptable accuracy standard out to a specific distance which is about 250-300 yards. Additionally, it stops the knuckle head from making sight corrections because the shooter "missed low" at 25 yards. Try to teach that to a bunch of new shooters! KD range teaches the trajectory/POA to compensate for distance.

    To illustrate sight height effect by method. Some shooters use an app or computer. In the application which I have on my smart phone, it has an entry for sight height. When you enter this data it will show you where the POI should be at a specific distance increment.

    If you put in 1.5" as the sight height with a zero range of 100yds, zero height at 0inches (Most hunters zero for 3inches high at 100yds), with say a .308 155gn Nosler HPBT@3000fps for example, it will use the Coefficient to determine the POI at distance. With a 1.5 inch sight height the POI will be .74inchs LOW at 25 yards, .23 inches LOW at 50yds and zero at 100yds.

    Change the zero distance to 25yds, and your zeroed at 25 yards ,1.25 inches high at 50 and 2.94 inches high at 100yds, and 2.23 inches low at 300yds. If you leave the sight height at 1inch you will be 6.73inches low at 100yds, 0inches you will be 18.73 inches LOW at 300yds!

    All that to say, there is a trade off considered acceptable to most shooters.

    My .02

    Mark

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