Any tips or tricks to get an "initial" center on the front and rear sights on a Sig when changing them out since both are dovetailed into the slide?

I have only ever replaced sights on Glocks. With the front sight mounted in the hole on the slide, it has been far easier for me to eyeball a center on the rear sight and then adjust as needed from there.

Any advice is greatly appreciated!

Although it sounds better than it actually works, mark the trailing edge (as they’re removed) with a pencil mark on the bottom of the dovetailed slot. Install the new sights so that their bases line up with the marks. That assumes, of course, that the bases are the same width as the originals’ are.

Alternately, mark the centers of the original sights with pencil on the slide and install the sights so their centers line up with the marks.

Just use your eyeballs. Then go shoot and seee where the shots hit. Shot placement is more important than the sights being centered, in my opinion.

 
I use the eyeball method to verify they haven't drifted over time. It is pretty easy to see that the margins on each side of the dovetail base are the same.
 
When installing for the first time, I measure the distance from the dovetail base to the end of the dovetail cutout using a 6" rule graduated in mm and .5mm. I use mostly the mm side of the rule, because it is easier for my eyes to see the graduations, and I can approximate any "in between" measurements.

Since my sight adjustment tool won't fit my P320s, I have to drift the sights. If you have access to a vice and a set of calipers, it gets you extremely close to perfect.

I taped some thin cardboard to the jaws of my vice, to keep from marring the slide's finish. Put the slide in the vice so that the sight base is slightly below the top of the jaws. Measure from the base, or blade of the sight, to the inside of the jaw. Measure the other side the same way. Drift the sight, as necessary, until centered.

I use the eyeball method. Changed front sight on my 229 last month and was actually closer to POA. Only took slightest adjustment.

Eyeball. I've installed sights on about ten of my own pistols. Sigs and Glocks. Use hammer/punch method. I eyeball the install and then go to the range.

Three quarters of the time the groups were perfectly centered. The times they weren't, I took the gun home and eyeballed the adjustment needed. Every time the correction was perfect. Obviously, if you used a sight tool, this could be done at the range.

I'm not sure if it is possible to actually measure the center of the sight and the center of the slide and then produce a centered group. Not only manufacturing tolerances, but some guns and shooters just shoot a little differently. All that matters is centered hits for you with your own individual pistol.

I used a brass drift and a small ball peen hammer for years, but found with my first Sig with night sights, that I just couldn't get any movement. I bought a pusher for around $50 or so, with inserts for a number of different pistols and have had good success with it.

As to centering the sight insert...I get it about centered, then go to the range (out my back door here on our farm) and shoot a cpl of groups of 5 shots each. I try to do it in the am with the sun behind me to get good, centered sight alignment...then back to the cellar and my pusher mounted in my bench vice. I've rarely had to do it more than twice to get a good POI/POA.

All of my Sigs needed tweaking for windage to some extent...and the last two (a M11A1 and a 225A1) needed a higher rear sight to get the impact point on the top of the front sight post at 25 yds. A #8 did it in both cases as the guns came with a #6 installed.

HTH's Rod

In addition to above, put a drop of oil on the dovetail and allow it to seep under the sight. It makes life less stressful.

I appreciate all the insights on this question. I have a plan on how to do this now, but just need to find the time to get it done.

Thanks!

I eyeball, but also use a small square for a "flat" surface. Lay that on the side of the slide and use a caliper to measure the distance between the flat surface and the side of the sight. Repeat on opposite side. This assumes, of course, the barrel is centered in the slide - easy to check also.

Eyeballing is usually pretty good - measuring is better.

I’ve got a sight tool for P Series Sigs. I just changed out the night sights on my P226 the other day. Well worth the investment if you have a few Sigs.

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