BUIS question, Glock 17 Gen 5 MOS

[Evil_Ed]

...are your BUIS actually useable? By useable - could you actually use them to shoot at and hit a target?

I ask because I bought a 17MOS, put on a Steiner MPS...it's awesome. I replaced the factory sights (which were dead on vertically at the 45 or so feet I usually shoot at) with a set of Ameriglo GL-429s...and it's easily 4 inches low at the same distances now when shooting irons. If I hang a 3x5 card vertically and aim at the top edge, I'll hit the bottom edge...again, at around 45 feet.

The front sight is seated firmly and deeply in the slide; it was tapped in with a delrin faced mallet and held in while the screw was screwed in, so I don't think it's that...

Is it just expected that BUIS on RDS-equipped guns will be just general ballpark "you'll probably hit the guy, more or less" sights?

I could call Ameriglo and see what they say I guess, I'm just not sure if this is "expected", or what. I have another G19 with a Holosun 508T on it, and an identical set of sights...I THINK they also hit super low but can't really tell, as the sights themselves are basically too short to actually be used on the gun - the RDS is too chonky. You can sort of barely make out the very tippy top of the front sight through the window when trying to use the BUIS on it but it's so tenuous that I wouldn't really consider it for BUIS use. I just never got around to getting a taller set of sights for it...but now I'm wondering if this is an inherent thing with these sights?

[RJ]

That seems odd. GL-429s are .315 Front, .394 Rear, I believe. What heights were the "Factory" sights? Specifically, was the front a 0.200"?

As a contrast, using the BUIS, my G19 MOS shoots POI=POA with range ammo (AE 124), using a dot hold, with a set of Ameriglo GL-470(.350 Front, .429 Rear). I ended up with the GL-429s so they would clear the optic / plate (HS 507c + FC Plate).

[WobblyPossum]

I have a set of GL-429s on a G19-5 MOS and have the same experience. They shoot about 6.5”-7” low at 25y with 124gr +P Gold Dot. The math says I need a .270” front sight so I’ll eventually order a Dawson in that height. Ameriglo doesn’t sell a .270” front. Other people have told me the same sights also shot low for them too.

[UNM1136]

I am coming to the position, that when it comes to pistol sights, if Dawson is an available solution, Dawson is the answer. (To parphrase Uncle Pat)

CS was a little pissy when I complained that they sent me the wrong sights, until I sent photos of the sights, the part number stamped into them, and caliper measurements. Then they fell all over themselves to replace them at their expense.

In a couple of weeks I am ordering Dawsons for my G17.4 work gun wearing an RMR for a lower 1/4 cowitness, fiber optic front and all black rear.

pat

[RJ]

...I ended up with the GL-429s GL-470's so they would clear the optic / plate (HS 507c + FC Plate).

I completely mangled this sentence due to lack of coffee this morning, I am currently using GL-470s, not GL-429s.

https://ameriglo.com/products/details/gl-470

[RJ]

In the event it's helpful, I'm going to re-post the links to the two Google Sheets I made to estimate windage and elevation corrections. As an example, I put in the numbers for the OP's situation (Glock 17, 45 feet) at the bottom to show how the elevation calculations would work to predict the ideal front sight height.

TL;DR: If you currently have a 0.315" front sight, a new shorter front sight of 0.267" should correct a 4" drop at 15 yards.

PS: I also suspect a shorter front sight would be even harder to see over the optics (It would be in my case) which is another reason I ended up with the GL-470s.


First, the background/repost:

I've been swapping carry guns like crazy this year and have been always messing with the sights to dial them in for how I shoot. I can never remember the formula for how much rear sight movement ends up shifting groups at the target.

So being kind of a math nerd, I knocked up a quick calculator to take my observations at the range and help me determine how much I have to push the sight. But I also wanted it to calculate how much of a turn of the threaded rod on my tool, would equate to that amount, since I have no way of accurately measuring really how much the rear sight actually moves in the dovetail. This way, I can assemble the tool on my slide, snug up the piusher block up onto the sight, turn the handle the predicted amount, and be pretty much spot on from then onwards.

I decided to do put this all a shared Google Sheets spreadsheet.

It's the first time I've worked with Google Sheets. If you click the link, hopefully you'll see a spreadsheet. You basically enter four pieces of data, and it will calculate both the rear sight movement, as well as how much fo a turn you need to make on the sight tool. The sheet is protected from edit, except for these four values. The sheet is "live", in that anybody with the link can get to it to use the tool.

Same for the elevation spreadsheet, you enter the data specified, and it will compute the new front sight height to achieve "zero".



Link to the Windage Tool

https://docs.google.com/spreadsheets...it?usp=sharing

Link to the Elevation Tool

https://docs.google.com/spreadsheets...it?usp=sharing

Example:

Entering a G17 sight radius of 6.5", and a distance of 45' (15 yards), and the OP's observed error of 4 inches, with a GL-429 sight height of 0.315", I get a new SHORTER front sight height of 0.267". In other words, the math suggests if need to raise your groups by 4" at 15 yards, you need to put a shorter front sight height on, of around 0.267".

[Evil_Ed]

Wow, awesome, thank you! I'm glad to read it's not just me running into this issue...Ameriglo sells a .285 front sight which is "close" but not quite I guess. Between the posts above and then even plugging the same info into Dawson's front sight calculator, everything comes in between .265 and .270 for a front sight....267 seems to split the difference just about perfectly.

The funny thing is, I look at Dawson's MOS sights and they have them at just about the same size rear but a .405 front? Which seems monstrously huge...

[DaBigBR]

The 429s for me are perfect at 25 yards on my Gen 5 Glocks. I have several with either those sights or the same heights from 10-8 (17 MOS, 19 milled, 19X milled, 34 MOS, 45 MOS).

I guess my question is whether or not a few inches is really enough to "matter." When you stack the following factors:

-Low probability of being in a shooting.
-Low probability of optic failure.
-Low probability of distance being great enough to matter.

...is it really, truly an issue?

I don't want to come across careless, but I think sometimes we get wrapped around the axle on what we want a "backup" anything to do for us. Obviously the cost to potentially correct it is pretty low, so that's a factor, too.

I honestly don't know how I would feel if it were my gun because it just hasn't been an issue for me.

[spelingmastir]

The 429s for me are perfect at 25 yards on my Gen 5 Glocks. I have several with either those sights or the same heights from 10-8 (17 MOS, 19 milled, 19X milled, 34 MOS, 45 MOS).

I guess my question is whether or not a few inches is really enough to "matter." When you stack the following factors:

-Low probability of being in a shooting.
-Low probability of optic failure.
-Low probability of distance being great enough to matter.

...is it really, truly an issue?

I don't want to come across careless, but I think sometimes we get wrapped around the axle on what we want a "backup" anything to do for us. Obviously the cost to potentially correct it is pretty low, so that's a factor, too.

I honestly don't know how I would feel if it were my gun because it just hasn't been an issue for me.

It's a personal choice and comes down to what you want to be able to do. Many people can't hit a sheet of paper from 25 yards so inches won't matter.

[Wayne Dobbs]

The chart is nice, but the formula is easy to use:

Error (in inches) X Sight Radius (inches)/Range (inches) = amount of correction needed

So the OP has 5" of error (based on top hold/bottom strike on a 3x5). Therefore,

5" (error) X 6.5" (sight radius) = 32.5

32.5/540 (45' converted to inches) = .06"

In this case, we need a front sight 0.06" shorter or the same taller dimension on a rear sight. Ameriglo likely has front sight blades that will accommodate that or you can file the front down, which was a time honored tradition starting in the Colt Model P days.

I have two Glocks with GL-429 sets and they both hit center at 10 yards. Odd that those don't.