POI change by sight height

[bearandoldman]

Guys need some help, been too long since I did this kind of calculation
Sight radius to make an even number 6 inches
Target distance is 25 feet x 12 = 300 inches
300 divide by 6 = 50
if rear sight is moved by .010 inches, POI will move 50 x 0.010 or .500

Guys does this make sense, I graduated high school in 1950 and retired 8 years ago, don't do these calculations often enough to keep up with it. Wnat to put a fibre optic sight on that is higher than stock and as trying to figure the rear sight height.

One of you young un's help the oldman

[k2ue]

Yes, that's correct.

[texasbatman]

Bear Etc. :)

Your math is 100% correct. It's like riding a bike.

Jim

[gottripletsNC]

Sight radius to make an even number 6 inches
Target distance is 25 feet x 12 = 300 inches
300 divide by 6 = 50
if rear sight is moved by .010 inches, POI will move 50 x 0.010 or .500




Ok, I must not be reading something right here, the math looks good, but its like I am missing something here, how does moving the sight .01 make the POI move .5. Is this a formula for sighting or is this just plain math and I am missing something...
Its late, I've been in class alot lately at work, and I have three kids, my mind just aint hittin much lately LMAO

[bearandoldman]

it's the ratio of the sight radius to the target distance. TD is 50 time SR, therefore every .001 of sight height moves POI 50 times or .050 for every .001.
Say hello to them sweet little ladies of yours and to thim mother also.

[bearandoldman]

Bear Etc. :)

Your math is 100% correct. It's like riding a bike.

Jim
damn, maybe I've still got it,

[bearandoldman]

OK, that's aboit the same as the on I posted. I want to put a HiViz on my Micro and it is higther than the present front sight and I have an SA adjutsble sight for the rear and was trying to fogure if they would work, As long as I can adjust the rear sight higher than the front I should be able to make them work. And it looks like th rear will go high enough will install them next week ad give it a try.

[cottontoptexan]

You guys stumped me for a minute. I set up and algebraic equation and then the old man throws tha Old Math at me and blew me out of the water for just a second. I use X as the unknown variable and as my Dad used to say WHAT IN THE HE???// is X .
You got it right just used good arithmatic. Curt in Wash

[bearandoldman]

Curt, it's still the middle of the night out ther in WA. Where you locted, my oldest son live just outside Portland Oregon? Also know a Gary Schnoist runs a sporting clays and hunting preserve and raises dogs on the east sid eot the state uses e mail of winterhawkpups.
Us old guy stick to th old simple stuff, Hell when I was young ther was no such word as COMPUTER. :D

[John Lawson]

According to my recollection, a movement of 29/100,000 of an inch per inch of sight radius moves POI 1 MOA.
Now, do you see why I love my laser bore sighting device?

[bearandoldman]

According to my recollection, a movement of 29/100,000 of an inch per inch of sight radius moves POI 1 MOA.
Now, do you see why I love my laser bore sighting device?
Hi ther John Law and a woo from the Bear too. Been giving some thought to buying one of those, they are not really that expensive. How do you use one. clamp the gun in a vise and project a spot on tha wall and then move the sight to cooincide? What kind do you have and where did you get it.

[John Lawson]

I have a 9mm device that I bought from Brownells. It works with 9X19, 9X21 and 9X23. When I get rich I will buy a .45 to finish off what I modstly use. It cost $150. I'd say it is well worth it.
There are several kinds that work with bore spuds, where mine is a cartridge like device that slips into the chamber. These bore types are adaptable to several calibers and are less money.
I also use a collimator that projects a virtual image to infinity and is good on handguns and superb on rifles.
If you can install an offset mirror to view your bore, you can set up a 3X5 file card on a wall a few feet away and mark the center of the bore and the line of sight (with an assistant. ) Then, you cross the line of the sights below the line of the bore the desired amount to get a pretty close poi.
Obviously, the collimator and lasers are much faster.
Neither the collimator nor the lasers will account for muzzle flip, so you are dealing with approximations. You can predict an X with a rifle or when your customer knows how to hold a pistol rock steady.
I also have a fixture that uses a dial indicator to visualize sight changes as measured from bore centerline.
I usually get the shooter to manipulate the sights after he hand holds them. That way, any refraction from my glasses does not interfere and need not be corrected on the range by the shooter.
Using a pistol bench rest (NOT a Ransom rest) you project the dot and crank the sights to coincide at the actual range you choose.
Woof, yourself, Bear. Waldo is too busy chewing on a dried pig ear to bother talking with anyone.