Been shooting a while, and I've been thinking, I'm pretty consistent now in my POI. The thing is, my POI is typically a bit high, say a couple inches, from my point of aim.

I was looking at my Trijicon HD sights, in relation to the stock sights. I noticed that the stock sight heights were much more aligned, in relative height, than the heights of the Trijicon sights.

So, I collected some data on sight dimensions from around the web, and, using the Trijicon OEM data, did the following analysis (all using height above slide):

Stock S&W FS9 (unverified numbers, web search)

Front Sight
Width: 0.130, Height: 0.160 (from slide), 0.230 (total)

Rear Sight
Notch: 0.140, Height: 0.170 (from slide), 0.240

Trijicon HD SA137Y (Trijicon web site)

Front Sight
Blade Width (A) Blade Height (B) Overall Height (C)
0.144 in. 0.215 in. 0.282 in.

Rear Sight
Notch Width (D) Blade Height (E) Overall Height (F)
0.169 in. 0.292 in. 0.382 in.

1) Stock Angle over sight radius:

Tan( ) = (0.170 - 0.160) / 6.5" = 0.01" / 6.5"

( ) = 0.0881 deg

(Meaning this is the "angle" subtended by the stock sights, along the 6.5" sight radius)

2) Trijicon HD over sight radius:

Tan( ) = (0.292" - 0.215") / 6.5" = 0.0770" / 6.5"

( ) = 0.6787 deg

(Meaning this is the "angle" subtended by the HD sights. Note it is a bit "more" since the site height ratios of the HDs are bigger than stock.)

3) Difference between sight radius "angle", HD and Stock:

0.6787 deg - 0.0881 deg = 0.5906 deg

(Meaning HD sights heel the pistol up, in elevation, 0.5906 deg "more", than the stock sights.)

4) What is the effect of 0.5906 deg over 7 yd / 21 ft / 252 inches:

Sin ( 0.5906 ) * 252" = 2.59"

(Meaning HD sights will shoot 2.59" higher than stock, all being equal.)

I shoot almost exactly 2 to 3" high on my M&P FS9 at the range.

I think it's the Trijicon HD sight height differences.

Am I wrong?

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Take your time, fast. J.Hughes

This made my head hurt. Also, I'm not very good at math.

^^^muahaha, mine too!


Llando I thought you loved Trijicon HD Night Sights?

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M&P OTAKU

I would like night sites for my mp 4inch 45 its a tack driver with fact sites , I looked at ameraglow and they looked just like fact smith site for 100 bucks . Will it shoot the same

I do. Very easy to pick up quickly. I also find the yellow better to see since I"m a little color blind.

But.

The math works, and it matches EXACTLY what I am seeing at the range, consistently, on POI.

The consistency of my high shots is just too weird. So, it seems to me that, in this case, it might "be the gun" instead of me heeling the pistol.

Not sure what to do about this. It just struck me as odd.

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Take your time, fast. J.Hughes

I have the SA137 sight sets on 3 M&P pistols and none of them shoot high...they hit the same as factory sights.

I will say this...on these sights sometimes the dot on the front sight may be off in relation to the dots in the rear sight, if only by a little...try lining up the sights independent of the dots and see if that fixes the problem. The dot in the front sight may be low in the front sight, which would cause you to hit high if you're trying to line up the dots instead of the sights they're mounted in...

Thanks. I always line up the top of the sights which bisect the center of the target.

This picture from july is typical.

I shot seated, with the butt resting on the bench.

Note group is about 2" or 3" high. Weird.

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Take your time, fast. J.Hughes

Right then, let me indulge in some more math.

Using the calculator on the Dawson Precision web site, it says I can calculate the front sight size per:

Sight radius * impact distance / target distance.

For my situation, this works out to

6.5" * 2.59" / 252" = 0.0668"

Meaning I need a front sight that is 0.0668" higher than what I have now to be zeroed.

If I theoretically added this distance to the current Trijicon front sight height, to make it higher (i.e. Tilt the bore axis "down" a bit):

0.215" + 0.0668" = 0.2818"

Meaning, ideally, I need a front sight that is 0.2818".

Recall the rear sight height of the HDs is 0.292". The difference would then be 0.0102".

The stock sight "difference" is 0.170" - 0.160" = 0.010".

How interesting.

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Take your time, fast. J.Hughes

I have a set of the Trij HDs on a G26. I hadn't noticed that the POI shifted with proper sight alignment, and I've shot with them out to 50 yards. One thing I have noticed is that some shooters may focus on placing the big Orange dot center of the target, which may result in higher bullet impact than intended.

PS I use sight picture #2, consistently:

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Take your time, fast. J.Hughes

Thanks.

I'm wondering if it's the other way around for me.

Lining up on the top edge vs. the dots.

Maybe the HDs need to be lined up "on the dots" because the geometry is designed that way by Trijicon and NOT the top of the HD sights?

I mean, these guys have A LOT of experience designing gun sights, so I am wondering if I Am Doing It Wrong.

If I switched to sight picture 3, the geometry would change. Notice the image assumes the dots are equidistant from blade height, front to back. Maybe, that IS NOT the case, for HD sights???

Hmmmmm...

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Take your time, fast. J.Hughes

Would you say you used sight picture #3 with the HDs?

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Take your time, fast. J.Hughes

Yes. Number 3 is always what I use with defensive pistols. I put the sight over where i want to hit...

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M&P's and K Frames Pleeze!

I just sent a request for clarification on this issue to Trijicon customer service. Will post back if they come back with an answer.

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Take your time, fast. J.Hughes

I sent a note to customer service:

"Sir: I have a 11/13 build S&W M&P FS9mm with a set of Trijicon HD SA137Y night sights. For best accuracy, should I align the tops of the blades, or should I align the center of the dots? I seem to consistently shoot about 2.5" high of POA when I align the sight picture to the tops of the blades. Thanks for any clarification on this. V/R llando88"

To their credit, I got a prompt reply:

"Thank you for contacting Trijicon. Using the top of the blades should have worked. However, because all slides are different, POI/POA may vary. Try lining up the lamps. If it still does not work, please contact us for further assistance. Have a great day."

Unfortunately, I have indeed tried 'covering the dots'. However, I still shoot about 3" high at 7 yards.

From looking at the HD sight elevations above the slide, I guess my question boils down to this.

In comparison to the stock S&W sights, the rear Trijicon HD sight top edge I received in my kit is MUCH higher, in relation to the stock S&W rear, than the front HD sight is, in relation to the stock S&W front.

In other words, if you were to look at the stock sights, laid along the slide, next to the currently mounted HD sights, it is obvious that the gun will angle up slightly, if aligned to the tops of the HD sights, as compared to stock S&W sight setup.

At this point, I am probably going to remove the Trijicon HD sights altogether and replace with the stock sights, or find another Tritium/FO sight manufacturer.

Sigh.

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Take your time, fast. J.Hughes

I received a nice follow up from Trijicon.

The gist of it was they suggested I purchase a slightly (0.010") higher front sight. Having spent $150 already, I'm going to pass on that option.

The inaccuracy, for me, of the HD sights, vis a vis POI to POA at 7 yards, relative to the stock sights, when shooting using a top of blade sight picture, OR when 'covering the dots', is troubling. I fully understand it could just be me. But I believe this inaccuracy corresponds directly to the (in my opinion) incorrect rear sight / front sight height choice that Trijicon select for the M&P sight package.

At any rate, I will chalk this up to a life lesson, and pursue an aftermarket sight option with e.g. Dawson Precision, that matches more closely the stock S&W sight height differences, for my application.

Great sights, the HDs, just not for me I guess.

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Take your time, fast. J.Hughes

I have seen no mention of bullet weight here. I have two guns with these sights mounted. My 9mm shoots low with 115 and my 10mm shoots high with 180 so I'm going out on a limb here and submitting that they optimized the HD sights for 135 grain bullets splitting the difference between 124 and 155's??? Defensive weight bullets not target ammo?

I too wil take the Dawson route next time. Something about my bullets going where I aim without offsets appeals to me.

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This≠DodgeCity&You≠BillHickok

I swapped out the VTAC rear for 10-8's version of a black VTAC replacement and have been very happy with that set up.

Up front I kept the VTAC FO/tritium and so far it's the best of both worlds.

Did she give any response to your opinion and data that the package they are offering for the M&P is slightly off and one of the sights should be switched in the package?

Ah. My bad. It was a mix of 9mm 115 and 124 FMJ RN. Either Federal (WalMart) or Freedom Munitions, both new brass and reman.

Approx 1,400 rounds since Jan 14.

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Take your time, fast. J.Hughes

Nope.

Just

1) shoot so that the tops of the blades are aligned and

2) they sell a 0.010" higher front sight I could buy if I wanted to.

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Take your time, fast. J.Hughes

Not to keep banging on with this, but I thought I'd log a couple 'before' pictures, showing the Trijicon HDs along side the stock sights.

So I held the stock sights as best I could. Forgive my non existent photo skills:

Rear:


Note how high the Trijicon rear is.

Front:


The front is not quite as high as the rear.

So, anyway, going forward, I've narrowed it down to the stock sight (blacked out) paired with either a Dawson Precision FO *or* a 10-8 FO.

Both are available at the stock height of 0.160".

Leaning to the 10-8, have heard it may be mounted slightly more robustly? Any inputs on this appreciated.

I'll post back with what I end up with.

Rich

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Take your time, fast. J.Hughes

I shoot site picture #1 referenced at toward the top of the posting. I chalked up to the tall sights and got comfortable with it. It did take a few rounds to conclude it was the sights.. still my favorite day-to-day shooter.