Question about dialling in my Glock 17?

[nternal]

I recently got a Glock 17 equipped with trijicon night sights. The sights were supposedly factory installed but I have my doubts because the front sight came loose and fell off after a few hundred rounds of shooting. I had the store where I bought it reinstall the front sight with a bit of lock tight to ensure this didn't happen again. The gun is squared away now and, after another 2000 rounds, I find that it shoots a little bit high. I had an expert marksman check it out and he concurred. I find that I have to line up the front sight about 1mm lower than where it should be to be properly centered with the rear sights. I have 3 questions about this issue:
1) Is there a spacer used with the trijicon front sight that I may have lost when it fell off?
2) Would it be possible to place a small shim under the front sight to lift it that tiny bit it would take to get it dialled in perfectly?
3) If there is no way to modify the trijicon sights can anyone recommend a high quality adjustable night sight?

[SamuelBLong]

I recently got a Glock 17 equipped with trijicon night sights. The sights were supposedly factory installed but I have my doubts because the front sight came loose and fell off after a few hundred rounds of shooting. I had the store where I bought it reinstall the front sight with a bit of lock tight to ensure this didn't happen again. The gun is squared away now and, after another 2000 rounds, I find that it shoots a little bit high. I had an expert marksman check it out and he concurred. I find that I have to line up the front sight about 1mm lower than where it should be to be properly centered with the rear sights. I have 3 questions about this issue:
1) Is there a spacer used with the trijicon front sight that I may have lost when it fell off?
2) Would it be possible to place a small shim under the front sight to lift it that tiny bit it would take to get it dialled in perfectly?
3) If there is no way to modify the trijicon sights can anyone recommend a high quality adjustable night sight?

1) No
2) Possible, but not recommended at all.
3) The rear can be lowered - again... not recommended; Dawson Precision makes a rear adjustable tritium.

but before you go swapping rear sights or modifying the trijicons...

1) how far off is "a little bit high"?
2) what distance are you shooting at to establish zero?
3) what hold are you using - drive the dot or 6 o'clock?
4) have you shot multiple types of ammo and bullet weights?
5) were your groups and your expert's off by the same amount of deviation?

[JHC]

Great list of followup questions by Sam. A little more info would be ideal.

Several of our Gen 4 Glocks shoot quite high (POI 8" above POA) at 25 yards FWIW. Taller front has remedied that.

[JV_]

(POI 8" above POA) at 25 yards

I would send that gun back, that requires a sight adjustment of almost .050"!

[JHC]

I would send that gun back, that requires a sight adjustment of almost .050"!

That's not unheard of with Gen 4s. Crazy eh? .250 tall has gotten then such that a 6:00 hold on a 4x6 will put rounds on the card. And since 6:00 hold is my lifelong habit . . .

[nternal]

but before you go swapping rear sights or modifying the trijicons...

1) how far off is "a little bit high"?
2) what distance are you shooting at to establish zero?
3) what hold are you using - drive the dot or 6 o'clock?
4) have you shot multiple types of ammo and bullet weights?
5) were your groups and your expert's off by the same amount of deviation?

1,2) To put rounds on a 4x6" metal target at 20 meters I need to place the top of the front site about 1mm below the line made across the top of rear site (I employ a POA sight picture). I'm not an experienced enough shooter to fully understand the mechnanism but I seem to need to line up the rear sites a tiny bit above the front sites at anything from 7-10 meters. I know that doesn't really make sense but since I'm shooting 4X6" metal targets I'm probably making miniscule unconcious adjustments at these different distances.
3) I'm using POA (Target is obscured by my front sight. I guess this is called "driving the dot")
4) I haven't taken bullet weight into account and was shooting 124 gr standard pressure.
5) If I remember correctly the "expert" who checked it (Slavex) was shooting about 1/2"-1" high at 5 meters.

Ps. It was coincidental that this slight discrepency was pointed out by my coach just before I started shooting metal targets that could give me immediate feedback on how my sight picture and trigger control were effecting my accuracy.

[nternal]

Based on all the variables of bullet weight, target distance and sight picture employed I probably need adjustable sights to fine tune my gun to my own exact requirements. Am I going to be creating a whole new set of problems (such as establishing a baseline from which to work) with something a like Meprolight Tru Glow adjustable sights?

[JBP55]

Based on all the variables of bullet weight, target distance and sight picture employed I probably need adjustable sights to fine my gun to my own exact requirements. Am I going to be creating a whole new set of problems (such as establishing a baseline from witch to work) with something a like Meprolight Tru Glow adjustable sights?

You may not have the correct sights for your pistol. The height of the front sight should be .165 and the rear should be .256 for a G17.

[nternal]

You may not have the correct sights for your pistol. The height of the front sight should be .165 and the rear should be .256 for a G17.

I doubt they are the wrong ones since they were supposedly factory installed by Glock and the store I bought the gun from is one of the most reputable gun shops in Vancouver. I also don't have a micrometer with which to measure them.

[SamuelBLong]

If you were lined up on a paper target at 20m... The tip of your front sight was level with the top of the rear, and the dot superimposed over the center of the target, how far off would the bullet impact be from the center of the target? Is it impacting at the tip of the front sight or is it higher than that? In order to figure out exactly how many thousandths of an inch off your sights are, we really need to know deviation based on a perfect sight picture (equal height w/ equal amounts of light on either side of the front sight).

I doubt they are the wrong ones since they were supposedly factory installed by Glock and the store I bought the gun from is one of the most reputable gun shops in Vancouver. I also don't have a micrometer with which to measure them.

You might want to make sure that they didn't accidentally install the G20 / G21 sights on that gun. It would be very helpful if we had actual measurements. Surely someone you know reloads and has calipers that you could borrow.

It wouldn't be the first time someone had that exact problem with a 9mm gun. My G26 arrived with G21 sights on it.

Based on all the variables of bullet weight, target distance and sight picture employed I probably need adjustable sights to fine tune my gun to my own exact requirements. Am I going to be creating a whole new set of problems (such as establishing a baseline from which to work) with something a like Meprolight Tru Glow adjustable sights?

As for stepping in a new mess if you get adjustable sights... If you're going to install adjustable sights, get the full set (matched front and rear), and you shouldn't have any issues. Center up the rear adjustments both in windage and elevation and shoot for record. There should be enough adjustment to get the gun zeroed as you want it to be.

You're just going to have to put in the time to shoot very accurately at the intended zero distance, so that you can precisely and accurately dial in the sights.