Last edited by ucrt; 08-09-10 at 21:03.
Why aim for the bottom of the triangle and not the center of the circle?
Sorry if this is a dumb question, but I zeroed my ar's by aiming in the middle of a circle at 25 yards and grouping them within.
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Then, you have a 25-yard zero and not a 50-yard zero. This means you'll be higher than 1-1/2" at a hundred yards and I think you'll be over 300-yards (closer to 400 maybe?) before you bullet crosses the line of sight again.
Without shooting at the intended long range, 25-yard zero is only good for "maybe" getting you on the paper for long range shooting...unless you only want to shoot close range"?
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Last edited by ucrt; 08-09-10 at 22:09. Reason: Clarity
Just to make sure I understand this correctly- You do the sighting in at 25 yards but this method gives you a 50/200 yard zero? Or is it zeroed at 100 yards?
If not what am I missing here? What two points will the bullet cross the line of sight?
Thanks for the clarification I can be a little thick headed sometimes
Last edited by rolltide13; 08-09-10 at 22:26.
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I feel inadequate explaining this but I'll try:
This target is supposed to compensate for being at 25 yards trying to get a 50-yard zero. Your bullet is still rising to the line of sight at 25 -yards for a 50-yard zero.
Most people want "point blank" range. This means your bullet will only be about 1-1/2" above or below the line of sight from 0 to about 225 yards.
Your bullet will cross the line of sight (los) at 50-yards going upward. It will rise about 1-1/2" above los around 100 yards and then start falling crossing the los again about 200 yards and then be about 1-1/2" below the LOS around 225.
Like Mark5PT56 said earlier, make sure to verify your accuracy out as far as practical.
Out to 225 yards, this 50-yard zero, will only help make sure you "maybe" hit the paper that far. If you intend to actually shoot out to 225 yards, you should shoot that far to verify. But I like to shoot 100 yards, then 200 yards, and then after you're zeroed at 200 (225), shoot again at lesser ranges to see where POI actually is.
Remember if you are off 1" at 50 yards, you'll be off 4" at 200 yards.
Did this get you good and confused??
Last edited by ucrt; 08-09-10 at 22:29.
The target shown in the OP, along with several other similarly designed 25yard "field expedient zeroing targets" are designed to get you "on-paper" at your desired "ZERO" (Point of Aim/Point of Impact) distance by adjusting your Point of Impact approximately 1.5" low at 25 yards. This method will give you a rough 100 yards Point of Aim/Point of Impact "Zero".
If you want a 50yard/225 yard zero, you should adjust your Point of Impact to be approximately 1.12" below your Point of Aim at 25 yards.
*IMPORTANT!!! YOU MUST CONFIRM YOUR ACTUAL ZERO AT THE DESIRED "ZERO" DISTANCE (100 or 50 YARDS). USING THE REDUCED "FIELD EXPEDIENT" 25YD TARGET METHOD IS JUST TO GET YOU IN THE "BALL-PARK" OF YOUR DESIRED ZERO DISTANCE.
Here is a quick video from Kyle Defoor on a 100M zero: http://www.kyledefoor.com/2009/10/carbine-zero.html
I use the same method, but I do it at 100 yards instead of meters.
ETA: A 50 yard and a 200 yard "Zero" are two different zeros. A 50 yard zero must be confirmed at 50 yards, and will give you a repeat zero at approximately 225 yards. A 200 yard zero must be confirmed at 200 yards, and you will usually be close to Point of Aim/Point of Impact @ 50 yards. (Usually within 1/4" or so @ 50 yards). Not a really big difference between the two methods, but they are NOT one in the same. Of course different ammo types, weights, etc. will vary your point of impact.
Last edited by nickdrak; 08-11-10 at 17:05.
What this is good for is getting you on paper @ 100. If you have a canted fsb you may not even hit paper at 100 your first time out.
"Oh, its a wonderful day! My sun is shining, my birds are chirping, my humongous chicken defeated Elmo." Huxley
Whatever distance you are at use the smallest circle, square, etc to zero on. What some find is what's "one the target" at 25 doesn't mean you are on at 100. ALWAYS CHECK AT 100!
I like a 1" square at 25-get the windage right and 2 of my fingers (point/middle) below the square and confirm at 100. It's always on because I get the windage right on. -years ago it was a 3" dot at 100--use a B8 target now.
GET IN YOUR BUBBLE!
There is a value in working through the zero process IMHO, especially in a class environment. I have been in classes where we rough zero low at 25, re-zero at 50 and then get to other things. I have also been in classes, like Randy Cain, where we rough zero low at 25, re-zero at 50, get a hard zero at 200, then check it again at 50. The remainder of the course is interspersed with more zero checks and fine-tuning. I have considered taking the class with my go-to rifle at least 25% of the reason being to get my zero locked in.
the hidden benefit of all this is that you're working the marksmanship fundamentals the whole time. Randy is sort of tricking you into becoming a better shooter while you're fine tuning your zero along the way. At the end of the class you're a better shooter with a good hard 200 yard zero that you've gotten to spend three days doping out and learning the hold-over/under for at various distances as well as when that matters and when it doesn't.
Not to pick nits but for someone having trouble with this concept, terminology may be important.
keeping the bore level; the projectile never "rises" to your line of sight, it starts falling the moment it leaves the bore.
Your sightline is a considerable distance above the bore, so by necessity your line of sight is angled down slightly. Your sightline travels in a perfectly straight line, the projectile travels in a downward arc.
So... Your perfectly straight downward angled sightline will intersect that downward arc in 2 places. Your near and far zero.
You can see in the below paint drawing (not to scale) how this plays out for a 50-225 zero. The red line is your trajectory, the black line is your line of sight raised above the bore and angled down. The blue lines at 50-225 show the intersection of trajectory/line of sight. The blue line at 25 shows why you want the rounds to impact lower than point of aim at that distance if you want a farther zero.
Edit to continue- tired of typing on an iPhone.
So, if you take the drawing and tilt the right side up so that the sightline is level (allowing you to see the target) the barrel will now be pointed slightly up. This is what gives the projectile the "rise" to meet the line of sight.
Most get this but, that drawing was made a while back for someone who couldn’t grasp that if the bore is level bullets don't "rise" and then fall. He was having trouble with the concept discussed here and that is what cleared it up for him... YMMV as I am not very good at explaining things...
Last edited by Luke_Y; 08-10-10 at 12:58.
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