I use this math often to demonstrate how terribly coarse in aiming precision iron sights really are.
Nice work Sheldon! Too bad wind will render your explanation almost useless.
....
Another time we were shooting at a thousand-yd. target when somebody asked how big it was. So we used a buddies mil-dot reticle at the optics highest power (not the mil-std. power) to "reverse-mil" the subtension at optic's highest power, then milled the thousand-yd. target in effect "reverse-milling" the target size and came up with like 30" (been awhile). When we measured the target it was .3" off from calcd.--couldn't believe it. Have done this sort of thing many times using calcd. subtension systems and absolutely know it has merit (i.e. better than guessing).
11,309.73355 / 180 (degrees in radius)
No-but it worked that time and if we didn't know the math we wouldn't have had a clue.
Are you saying shooters shouldn't know the math?
MD--in the interest of seeing about how lucky I was that day, I Just looked at the math and assuming a 1/2 mil subtension (1.8 IPHY) if the target was 23.4" (about that size--it's been awhile) figuring an interpolation accuracy of +/- .1 from 1.3 subtension units then there's only +/- 1.8" variation from that measurement. Interesting really--love this schit!No sir, just wanted to make sure we were being realistic here.
Also it's Cool, besides just saying the word subtension makes you look like your smart, huh? HA!
Alright, I know this is going to sound pedantic, but this is a pet peeve. I cringe when I hear someone say "one minute of angle is 1.047" at 100 yards".
Minutes of angle are units of angular measurement. A minute of angle is 1/60 of one degree of angular measurement.
An inch is a unit of linear measurement. A unit of angular measurement cannot become a unit of linear measurement and vice verse.
One minute of angle subtends one minute of arc on the circumference of a circle the center of which is at the vertex of that angle of minute. If the radius of that circle is 100 yards, the length of the arc subtended is 1.047". Note that this is a measurement of arc length, not a straight vertical distance as we are usually measuring off a target. But because the unit of angular measurement is so small, the curvature of the arc can be disregarded.
...11,309.73355 / 180 (degrees in radius)
...Answer from line one (radius) divided by 180 - one angle.
... ballpark range to 250 yards using my scopes parallax adjustment alone allows me to coarse adjust within those distances quickly in the field. Similar to PBR zero but I chart the drop and adjust elevation...
No major wind considers inside of there for my field conditions so it works well enough...
... A few streamers don’t bother the deer while offering yardage markers with wind indicators built in...
Are you seriously dialing distance for 250 yard shots at deer? I understand if you are shooting subsonics or pistol calibers and such, but that doesn't make much sense for any centerfire with muzzle velocity over 2500 fps.
Yes for muzzleloaders and straight wall cartridge. It may be an inch or two in some cases or a gut shot in others.
The rule is "hair under the sight." Never aim at thin air.
Let's imagine you have a .30-06 launching a 180 grain bullet at 2,820 fps (standard Hornady load.) If you zero to put the bullet 3" high at 100 yards (assuming you're using a reasonable scope -- not one of the monsters I see in the field nowadays) you'll be about 9 1/2 to 10 inches low at 350 yards. If the deer is 350 yards away (and that's waaaaay out there) and you hold just below the backbone, you'll get a perfect hit.
The rule is, a tad low when they're really close, under the backbone when they're way out there, and dead on for all other shots.
IF you can judge wind!!