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Thread: Sighting a Rifle at 25m for a 100m zero

  1. #1
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    Default Sighting a Rifle at 25m for a 100m zero

    Okay, so I'm in a slight pickle. I've been trying to understand how to sight it properly.

    Objective: 100m zero
    Range: 35m

    Rifle: Savage Axis .270 Stainless Steel
    Scope: Weaver 3x9 40mm
    Laser: StrongTools Green Boresighter

    I'm thinking, range at 25m and 3 clicks up to zero point at 100m. am I wrong?

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    As you're in pretty close at 25m , you have to accommodate the parabolic curve of bullet flight. The image below is a bit simplistic but gets the point across. The bullet rises quickly and then drops, so zeroing at 25m will be pretty far off. Of course that depend on the weight and velocity of the bullet.

    Nothing wrong with the initial setup up of the scope at 25m ( align the optical and mechanical axis). I do that and leave it about 1" high of POA. But I wouldn't trust the accuracy at 100m until I actually zeroed again at the 100m.

    note: if you're new to looking at bullet trajectory charts be aware they are grossly misleading because of scale. The rise ,'Y' is in inches and he 'X' is in yds ...so it's shows huge parabolic curves like you firing a mortar. The actual curve is really much slighter.



    Last edited by MikePal; March 10th, 2021 at 05:58 AM.
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    The reality and simple explanation is that you initially want to get on paper bullseye with your scope / rifle setup at 25 meters.
    Then you must proceed to fine tune at 100 meters.
    No escaping the need for this to ensure accuracy.
    Last edited by impact; March 10th, 2021 at 06:33 AM.

  5. #4
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    25 yard 0 and 200 yard 0 is kind of a rule of thumb for spitzer point bullets.Most Big game Calibers(unsure about Magnums)
    At the end -Your desire and your bullet will dictate where are You to be at 100 y.
    If You want to be 0" in general "at 200 y,You will be somwehat high at 100 y.That depends on your bullet(look up Ballistic charts for this).
    That will tell You (lets say should be at 1.5 " high at 100 y to be zero at 200 y)AND You are hitting 1.5 high at 100 y,but center,You made it.

    Still -need to verify the ranges You want to shoot at(like 50-100-200 y should be good enough for Ontario)
    Last edited by gbk; March 10th, 2021 at 12:33 PM.

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    In the second image that Mike posted, the bullet crosses the level line of sight around 35 yards and again at about 235 yards - which is your optimum sigh-in distance for that bullet/load configuration.

    IMO, folks that sight in for 100 yards/metres are short-changing themselves for longer shots as the line of sight is slightly negative (less than horizontal).

    The actual range and point of impact will vary due to the firearm and cartridge characteristics and weather conditions. Good luck!
    Last edited by Sam Menard; March 10th, 2021 at 10:41 AM.

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    Quote Originally Posted by Sam Menard View Post
    IMO, you should sight in for 200m which would put you about 2” high at 100m. Sightings in for 100m short changes you for longer shots.
    Better yet use the Maximum Point Blank Range (MPBR) system. Think of the kill zone as a piece of pipe and give yourself some room. For deer think of the kill zone as a 6in pipe, then you will have a couple inches up and down of error. Sight in your rifle so that you will never hit outside that pipe out as far as possible. For example, my 222 Rem is sighted in at 215 yards with a 50gr Vmax coming out of the barrel at 3220fps. That gives me less than 2in above or below the line of sight out to 250 yards. A coyote inside 250 yards I just aim for the center of the boiler room and pull the trigger.

    There are calculators online you can use if you know the velocity of the bullet and the profile but based on box ballistics you can get close by doing this MPBR system. The standard 2in high at 100 yards is fine for a good chunk of Ontario with anything in the 3006 class but if you take the MPBR system into account with 30-30, 45-70, 44 mag, for deer you can really stretch out the range with no hold over and for longer shots on moose or deer in open areas like around here you can really give yourself an advantage by using this method and knowing that you can shoot a deer on the other side of the field without guessing.

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    Quote Originally Posted by Fox View Post
    Better yet use the Maximum Point Blank Range (MPBR) system. Think of the kill zone as a piece of pipe and give yourself some room. For deer think of the kill zone as a 6in pipe, then you will have a couple inches up and down of error. Sight in your rifle so that you will never hit outside that pipe out as far as possible. For example, my 222 Rem is sighted in at 215 yards with a 50gr Vmax coming out of the barrel at 3220fps. That gives me less than 2in above or below the line of sight out to 250 yards. A coyote inside 250 yards I just aim for the center of the boiler room and pull the trigger.

    There are calculators online you can use if you know the velocity of the bullet and the profile but based on box ballistics you can get close by doing this MPBR system. The standard 2in high at 100 yards is fine for a good chunk of Ontario with anything in the 3006 class but if you take the MPBR system into account with 30-30, 45-70, 44 mag, for deer you can really stretch out the range with no hold over and for longer shots on moose or deer in open areas like around here you can really give yourself an advantage by using this method and knowing that you can shoot a deer on the other side of the field without guessing.
    Good advice. I didn't know it had a name (MPBR).

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    Quote Originally Posted by poltrojan View Post
    Okay, so I'm in a slight pickle. I've been trying to understand how to sight it properly.

    Objective: 100m zero
    Range: 35m

    Rifle: Savage Axis .270 Stainless Steel
    Scope: Weaver 3x9 40mm
    Laser: StrongTools Green Boresighter

    I'm thinking, range at 25m and 3 clicks up to zero point at 100m. am I wrong?

    How about your ammunition? Do you reload it or do you buy it manufactured. If you buy it, who is the manufacturer? Are you planning to use the ammunition from that manufacturer in an ongoing basis. Once you set the rifle in, any change in the components of the ammunition you use, is going to move your point of impact about. Beware ammunition manufacturers don't all use the same component regime. There are even variations to components from lot to lot with the same manufacturer. Such variations may not effect the point of impact a great deal, but it does make it difficult to consistently drive tacks. Just thought I should pass this information a long to you.

    You don't stop hunting because you grow old. You grow old because you stop hunting.
    - Gun Nut.

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    Quote Originally Posted by Gun Nut View Post
    How about your ammunition? Do you reload it or do you buy it manufactured. If you buy it, who is the manufacturer? Are you planning to use the ammunition from that manufacturer in an ongoing basis. Once you set the rifle in, any change in the components of the ammunition you use, is going to move your point of impact about. Beware ammunition manufacturers don't all use the same component regime. There are even variations to components from lot to lot with the same manufacturer. Such variations may not effect the point of impact a great deal, but it does make it difficult to consistently drive tacks. Just thought I should pass this information a long to you.

    You don't stop hunting because you grow old. You grow old because you stop hunting.
    - Gun Nut.
    Very good point-LOT control is very important. When figure out what You will shoot: buy 3-5 boxes of the same LOT.
    Or more-if You will be shooting volumes.

    You could bet on point of impact changes lot to lot.Maybe still OK for deer size target,but why taking chances.
    Last edited by gbk; March 10th, 2021 at 12:40 PM.

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    Quote Originally Posted by Gun Nut View Post
    How about your ammunition?
    Winchester 130/150 gr Super X Power Point. I bought both, but I'm thinking I will stick with 130 gr.
    Based on Winchester's ballistics calculator if I sight it at roughly 35-40 yards, the trajectory will zero in at 200 yards.


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    Last edited by poltrojan; March 10th, 2021 at 03:17 PM.

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