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I think you will find the sight movement on most Smiths to be the same per click. Which means POI impact movement will be considerably different on target with different barrel lengths. You can figure the math and predict POI movement, but movement of the sight is so slight with a handgun better way is to zero click some changes off and measure result on target

Formula from memory is distance divided by sight radius X movement of sight per click. It's a geometry quiz and I probably failed.

Boats
 

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Discussion Starter #3
OK, well I'm a schoolteacher on summer vacation, so I'm not doing any math til September!

I'll be more specific; Four inch barrel, shooting at 25 yards.

Any takers?
 

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It will vary between guns, because of the sight radius. There is a mathematical formula that works on gun sights.

SIGHT IN FORMULA
To determine the correct sight height to correct an elevation problem, multiply the sight radius, in decimals by the elevation error and then divide the results by the distance to the target, in inches.

Sight radius 5 3/4" = 5.75
Shooting 5 inches low
Distance to target 25 feet or 300 inches

5.75 X 5 divided 300 = .09583

The front sight would have to be lowered .096 inch or the rear sight raised that amount (or a combination there of) to raise the point of impact.



Sight radius 4" = 4
Shooting 6 inches low
Distance to target 25 yards or 900 inches

4 X 6 divided 900 = .0266

The front sight would have to be lowered .027 inch or the rear sight raised that amount (or a combination there of) to raise the point of impact.






OK, you want to adjust windage. The pitch of the windage screw is about .012 inch.
divided by 6 clicks is .002 thou per click.

If you say your off 1 inch at 25 yrds with a 4 inch N frame, it will be about 6 clicks to get in on target. Or more like 5/32 per click.

OK leave me alone I hate math. kihfL
 

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Magnum nut's got it cold. I have to look at my notebook to get the formula

Only thing I would add is measuring movement in very small increments is not easy. Only way I know to get it accurate on a pistol is use a dial indicator and measure each clicks movement. Most common reason to calculate is when fitting different sights. In that case I screw the rear down all the way sight it at 10 yards then run another group with the sight all the way up. Unless it's something special like a Silhouette pistol want the front sight to zero properly mid range of the adjustment on the rear. This 10 yard setting gives enough leeway for different loads and holds. The silhouette handgun you want at the bottom on Chickens leaving enough movement for all the targets as distance increases.

For a long sight radius like on a single shot rifle a dial caliper will give very good readings. Most have sight radius 10 times that of a handgun. However even though I calculate sight heights in advance when setting up a new rifle or pistol I still prove it on paper at short distance before doing any cutting or filing. Most of the time hose clamp or zip tie a cardboard or plastic front sight on cut to zero then set up the permanent sight from it's proven dimension.

More than you wanted to know.

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Then to make things worse, after your all happy the gun hits to point of aim, you change the load to something else.... ryperp
 

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Discussion Starter #7
Thank you all! I'll call it 6 clicks per inch or so for 25 yards for the windage. Is the elevation screw the same pitch?
 

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Having shot Ihmsa silhouette for the last 29 years, i can tell you from experience that smith & wesson
adjustable sights are generally not repeatable, as far as setting them for different distances. we use to use
feeler gauges to get repeatable settings for silhouette shooting, if you were using a stock model 29, for
example. If say your chicken settin was 4 clicks up from bottom, chances are the next time you reset it to that, it would not be correct. might shoot higher or lower. smith sights are very good for setting to ONE distance and then leaving them there. and the 29's back in the day would shoot completely loose within a
year, sometime less, if you shot lots of matches. pretty much why ruger took over revolver class cause they would take the beating better than the smiths. after dan wesson brought out the .357 super mags, the
rugers pretty much fell by the wayside, as the dan wessons were much more accurate.
 

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Now you have me guessing. I think the windage screws pitch is coarser than elevation screws. But looking at the S&W parts list they have different screws for different frame and barrel combinations. This probably to offset the short vs long sight radius issues as well as the cartridge trajectories.

But the book just says they are different does not give the screws pitch.

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Lockhart agree on the sight settings, Black powder cartridge silhouette I use a brass bar to set my ladder tang sight at zero which is 200 meters for Chickens. Work off the vernier scale from there. I could use the vernier to dial in the base setting but that bar is fool proof.

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Boats said:
But the book just says they are different does not give the screws pitch.

Boats
I used a pitch gauge and a windage screw in my hand to guess-ta-mate the pitch. You need a microscope to really see the threads. I figure they are about 80 TPI.

I would think the pitch would be the same for the elevation.

But when you shoot it, sometimes your eyes play tricks with you as you hit a little low, high whatever. It's a gun and you need lots of practice with the same gun / load to get really good at shooting. Temp and wind play into this too.

Go shoot it for real, the adjustments are close to what you will need to sight it in. hpzl;n;
 
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