How do I adjust a fixed sight auto-pistol?

[Commander Crusty]

Dear Gunsmiths,

I have a Ruger SR9 with drift adjustable sights front and rear. The pistol shoots pretty close to POA at 7 yards, but almost a foot right at 25 yards. Yes, I'm SURE it's the gun because the other two guns I shot at the same time shot just a bit left.

Can I use a steel punch to push the rear site? Or is it much better to use brass? Metal or rubber mallet? Is it best to disassemble the gun before I start bashing--er--tapping away? Should I use a vice or put the pistol slide flat on a piece of wood?

And is there some way to adjust the sight AT THE RANGE?

Thanks for your help.

 

[rcmodel]

NEVER use a steel punch! Ever!

I'd try a hardwood dowel or nylon sight punch first.
If that don't do it, move up to a brass punch.
Rub the sight with a lead pencil first so you can get the brass tracks off later.

Use a small steel hammer and try light strikes first.

Some of the new guns coming out now have Very Tight sights and will be very difficult if not impossible to move without damaging them unless you use a sight pusher.
And even then, some of them are just too tight to move.

rcmodel

 

[mort]

If you have some scrap brass flat bar and brass rod you could make something like this sight tool from midway.

http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=754137&t=11082005

All that you really need is a C shaped piece with an opening big enough to go around your slide, then put some threaded brass rod through one side of the C about half way up. Pin a knob on the end of the threaded rod and you have a sight adjuster.

 

[ranger335v]

I've never bothered with brass drift punches, just use the rim/extractor goove of an old rifle case as a pad and tap the sights over with a carpenter hammer.

Avoid clamping a slide in a vise, put a layer of cloth over a piece of hardwood and use that as a back-up, or "anvil". And don't move the sights much without trying them, it's VERY easy to go too far!

 

[W.E.G.]

I tried hammering the bejeezus out of a rear sight on a P95.

That sucker wouldn't budge.

I gave up.

The cone of dispersion of that gun at that distance pretty much had the area covered anyway.

 

[highlander 5]

There is a formula to figure how much you sight has to move left or right. take the distance you're off ( in inches) divide it by the distance you're shooting (again in inches) take this number and multiply by barrel length. this is how much you must drift your sight.
Brownell's has a very nice sight adjustment tool for around $100.
Use a vice that you put the slide in then move the sight via 1/4-20 cap screw that has a plastic protector on it

 

[Bob Rodgers]

Here's a little easier way for you to see the formula. Note that the SIGHT RADIUS is used as a value, not the barrel length.

The formula:
SR (sight radius)= distance between aiming surfaces of front and rear sight in inches.
D = Differences in point of aim to point of impact, in inches.
The third value is the distance at which the shots are made, converted to inches. (25 yards = 900 inches)
As written, the formula is: [SR(D)]/900 (sight radius times error divided by distance.
Sample problem: Sight radius = 6.5”
Shots are 3.0” low
Distance is 25 yards (900”)
6.5 X 3 = 19.5
19.5 / 900= .0216
Front sight must be lowered .021”

If the shot is LOW, the front sight must be lower.
If the shot is HIGH, the front sight must be taller.
The REAR sight is moved in the direction you wish the bullet to travel. If the shot is to the left, move the rear sight RIGHT.

Once you figure the correction needed, use a pencil mark along side the sight to help you keep track of your adjustments. No need to guess. The math doesn't lie and you can get it right on the first try.