300 yard zero???

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  • Striper69

    Ultimate Member
    Jan 31, 2014
    1,400
    Iowa
    The newest "Arms And Ammo" episode has a segment where a Special Ops guy says that a 300 yard zero has it's advantages. They use the 6.5 Creedmore as an example.

    I'm in the process of trying this out.

    Opinions. :)
     

    E.Shell

    Ultimate Member
    Feb 5, 2007
    10,244
    Mid-Merlind
    .308 sniper rifles had used a 400 yard zero for years. If the target shows up close, a slightly low hold makes the connection and for the longer shot of opportunity, one need only hold a little high.

    The 6.5 CM shoots so much flatter that moving the baseline zero to 300 yards simply makes sense and serves the same function.
     

    Hawkeye

    The Leatherstocking
    Jan 29, 2009
    3,971
    The newest "Arms And Ammo" episode has a segment where a Special Ops guy says that a 300 yard zero has it's advantages. They use the 6.5 Creedmore as an example.

    I'm in the process of trying this out.

    Opinions. :)

    A 300 yard zero for what? What rifle? What ammo? What purpose?

    The zeroing you choose for a given rifle depends on all of those things. Different rifles, with different ammo, will have different trajectories. In turn, the intended use for each of those said rifle and ammo combinations might dictate a different zeroing.

    If you're never going to be taking shots beyond 200 meters / yards with a given rifle, a 300m zero would be silly. Likewise, if you're never going to be taking shots closer than 300 m, a 100m zero would be silly.

    36 yard the same as 300 yard, correct? i do mine at 36 yards.

    https://www.m4carbine.net/showthread.php?65679-AR-15-Zeros-and-Trajectories

    It depends on the rifle and ammunition.
     

    ted76

    Ultimate Member
    MDS Supporter
    Jan 20, 2013
    3,151
    Frederick
    All of my long range hunting rifles have scopes with Bullet Drop compensators built in, as long as you have the correct turret on it, for your load and use a good range finder or are good at estimating distance, you are good to go.
     

    trailman

    Active Member
    Nov 15, 2011
    631
    Frederick
    Its my understanding that you zero at 100 yards or meters. Then work the math and recticle adjustments from there. I mean that's what the really big marked turret knows are for right?
     

    davsco

    Ultimate Member
    Oct 21, 2010
    8,607
    Loudoun, VA
    makes sense to zero (poa = poi) at your most likely target distance, especially if you will need to get off quick shots. but still have to know your come ups and come downs from that at other distances.

    that said, i zero everything (hunting, LR, tactical, etc) at 100 yds and just know (or use cheat sheet/data card) what my holds or dials need to be at other distances. my only 200yd zero is my 3 gun AR with the vortex razor hd 1-6 scope where their bdc reticle is based off of that. still, nothing but the crosshairs/200yd line up exactly so i have to know my holds vs the reticle hash marks at 300, 400, 500, 600 yds.
     

    Pinecone

    Ultimate Member
    MDS Supporter
    Feb 4, 2013
    28,175
    It depends on if you are dialing elevation or holding. And what ranges you shoot at.

    I am a fan of the maximum point blank range. This is zeroing so that out to the longest possible range, a center hold will deliver a hit to the vital area.

    For long range, I run a 100 yard zero. And unless you put on a huge angled base, the zero doesn't matter. You will still be at the same point in the adjustment range. Unless you have such an angle on the base that you cannot get down to a 100 yard zero.
     

    E.Shell

    Ultimate Member
    Feb 5, 2007
    10,244
    Mid-Merlind
    Referring back to the original post: That this would be discussed/recommended by "a special ops guy", and the actual distance recommended, would imply a simple battlesight zero. After that, no dialing, all holds. They've used scoped rifle BSZ of 400 yards for many years, but that was a .308. The 6.5's flatter trajectory would allow for a shorter base zero for the same maximum range.
     

    Hawkeye

    The Leatherstocking
    Jan 29, 2009
    3,971
    I started writing this earlier today and got distracted. So...

    Its my understanding that you zero at 100 yards or meters. Then work the math and recticle adjustments from there. I mean that's what the really big marked turret knows are for right?

    Again, it depends on what you're using and what you're doing with it. For my "go to" AR, which is a 16" barrel shooting 55gr Federal xm193 with a red dot on it, I zero at 100y. For that rifle, with that ammunition, that means that anything out to 200y will be within about 2" of POA. 300y will be about 9-10" low and 400y gets silly at about 26" low. However, with that zero there is never a "hold under," only a "hold over," and I know that realistically I'll never be taking shots at anything outside of a couple hundred yards anyways, so I am happy with the simplicity of a 100y zero.


    Safe to say these holds are using a mil dot reticle?

    Mils are a measure of angle, just like MoA (minutes of angle). It's just an SI (metric) measure instead of an English one. You can calculate holdover / holdunder in either system. Some reticles are set up with mildots (i.e. they measure in mils, or miliradians), and some are in MoA or other measures. Some have BDCs, or bullet drop compensators, which are generally set up for a specific load out of a specific barrel length and a specific zeroing distance. Then you just range your target and put the appropriate point in the reticle on it and shoot.

    If you know what your'e doing you can calculate a hold no matter which type of reticle you have.
     

    Biggfoot44

    Ultimate Member
    Aug 2, 2009
    32,881
    Post #9 and post #10 lay out the dueling philosophies back to back . And my take is ... not exactly either .

    I would slightly modify " zero AT your most likely distance " to " zero so as to not require meaningful hold under at most likely distances " .

    For Me ( and what I recommend ) is impacting no more 1.5in high . For deer sized ( includes upright 100-200lb critters ) , 1.5in can be effectively disregard , but meaningfully extends the farther point blank - ish range .

    My disagreement with the maximum point blank theory is its putting equal value upon holding under at more frequent distances, and hold over at longer distances . I despise hold unders , and accept reasonable hold overs .
     

    E.Shell

    Ultimate Member
    Feb 5, 2007
    10,244
    Mid-Merlind
    ...Mils are a measure of angle, just like MoA (minutes of angle).
    True.
    It's just an SI (metric) measure instead of an English one.
    Not Really. A mil is derived from a circle, and the exact dimensions and geometric relationships of the circle are in no way related to the metric system. Here is how it actually works:

    A "mil" (milradian) is 1/1,000th of a radian.

    A radian is an arc length along a circle's circumference that is equal to its radius.

    When we divide the radian into 1,000 parts (thus the prefix "mil" in milradian), each part is 1/1000th of the circle's radian AND radius. This means that we develop a 1:1,000 ratio between the distance from the center of the circle to the outer circumference and it is 1 milradian:1,000 milradians.

    When we measure angles at a distance, such as using mils to hold over or calculate range, we are using the principle of this simple 1:1,000 ratio.

    This renders the following facts:
    1 milradian (mil, milrad) is equal to the following:

    1 inch at 1,000 inches
    1 foot at 1,000 feet
    1 yard at 1,000 yards
    1 mile at 1,000 miles
    1 light year at 1,000 light years
    1 parsec at 1,000 parsecs
    1 meter at 1,000 meters (and this one aspect, of course, this is how it's a definitely a "metric" measure, LOL)

    The only reason it works any further with the metric system is the commonality of Base10, in that we divide mils into tenths and we divide meters into tenths. If meters were 2" long, or 4,000 feet long, the formulas still work...because they are based on ratios native to a circle.

    So, no, not exactly metric.

    By the way, there are 3.1415 radians in a circle, and that number should be familiar, because it's "Pi". This is why radius x Pi = the circumference.

    You can calculate holdover / holdunder in either system. Some reticles are set up with mildots (i.e. they measure in mils, or miliradians), and some are in MoA or other measures. Some have BDCs, or bullet drop compensators, which are generally set up for a specific load out of a specific barrel length and a specific zeroing distance. Then you just range your target and put the appropriate point in the reticle on it and shoot.

    If you know what your'e doing you can calculate a hold no matter which type of reticle you have.
    True.
     

    E.Shell

    Ultimate Member
    Feb 5, 2007
    10,244
    Mid-Merlind
    Post #9 and post #10 lay out the dueling philosophies back to back . And my take is ... not exactly either .

    I would slightly modify " zero AT your most likely distance " to " zero so as to not require meaningful hold under at most likely distances " .

    For Me ( and what I recommend ) is impacting no more 1.5in high . For deer sized ( includes upright 100-200lb critters ) , 1.5in can be effectively disregard , but meaningfully extends the farther point blank - ish range .

    My disagreement with the maximum point blank theory is its putting equal value upon holding under at more frequent distances, and hold over at longer distances . I despise hold unders , and accept reasonable hold overs .
    Philosophies being what they are, the overruling concept is "The Right Way, The Wrong Way, and The Army Way..."

    The thread's original post does not deal with hunting or recreational shooting. Somehow, our customary thread drift took it away....

    In combat situations, there is no time to think or dial. The customary 400 yard zero for a scoped .308 provides for instant action with the widest possible range capability for that load. If a target pops up at 100 yards, indicating great urgency in response, you need only hold 2.4 mils low of your desired impact point. 2.4 mils at 100 is only 8-1/2", so a belt buckle hold gets a center hit. If a target pops up at 700 yards, you need to hold up 3.9 mils, well within your 5 mil holdover span (customary mildot reticle), so you can react quickly with a simple holdover.

    If you are toting your .308 sniper rifle with a 100 yard zero and a target of opportunity pops up at 700 yards, your holdover of 6.3 mils exceeds your field of view and your 5 mil max holdover in a standard mildot scope. As you muse over what to do, you are shot.

    This is the concept of a simple battlesight zero, and it is not the same as an M-16/AR-15 because of differing optic heights over bore and because cartridge ballistics differ.

    There is a big difference between this tactical/combat shooting and hunting, both with respect to what works well, the time involved and the consequences should you not react in time.

    The new 6.5 CM load will provide much the same capability, but with a closer zero distance.
     

    Hawkeye

    The Leatherstocking
    Jan 29, 2009
    3,971
    Not Really. A mil is derived from a circle, and the exact dimensions and geometric relationships of the circle are in no way related to the metric system. Here is how it actually works:

    Thanks, Ed. I actually knew the math for the radian. The radian *IS* the SI unit of angular measure (it is technically an SI Derived Unit, since it is calculated based on the SI base units, but it is the SI measure of angle), and the miliradian is another derived unit that comes from the radian.

    You're correct that it is based on the mathematical properties of the circle, but it's the SI unit of angular measurement.
     

    E.Shell

    Ultimate Member
    Feb 5, 2007
    10,244
    Mid-Merlind
    Thanks Hawkeye.

    While the Meter is indeed an SI unit,a radian is not listed. They do not seem related in the sense of any characteristic of the radian dictating the length of a meter. Nor is a Radian listed as one of the basic SI units.

    From your link, one meter defines 1/10,000,000 of the meridian between Paris and the North Pole. I was unable to relate this distance to a radian, but my math skills are marginal - can you shed any light on this for me?
     

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