Sight question, how's sight height work?

[BehindBlueI's]

I'm probably overthinking this, but I'm afraid to jack up something that's working. Here goes.

I have a Sig P229 that shipped in 2001. The night sights, as you'd imagine, are nearly dead. I want to replace them with the Trijicon night sights with the white outline around the tritium vials.

The P229 was originally a .357 Sig. I generally carry and shoot with a .40 S&W barrel installed. The gun is currently very accurate, I can consistently (over 90%) hit an IDPA torso steel at 70y.

The front sight is marked "9" and the rear is marked "7".

Trijicon's sets for the Sig are either 8/8 or 6/8. 8/8 is for .40 or .45 and 6/8 is for 9mm/.357

What difference does the caliber make? Why is the .357 not with the .40? It looks like a 9/7 results in -.025" difference, 8/8 in -.030 difference, and 6/8 in -.020 difference. Does 5 or 10 thousands of an inch really make that much difference to have different SKUs, or is it not the difference between the two but the total height or what am I missing? I don't know which, if either, set I should go with or if I should buy a "9" and "7" separately.

[GJM]

Think you have it reversed -- 8/8 is for 9/.357 and 6/8 typically .40/.45.

Trijicon HD sights are marked 226/225/228 or 229/220, but the difference is that the 229/220 front sight is .225, and the 226/228 is .215.

https://www.trijicon.com/na_en/produ...dns.php?mid=15

Update, they now label them 9/.357 and .40/.45 instead of the model numbers, which was nonsensical given 226 and 229 can be 9 or .40.

[BehindBlueI's]

Think you have it reversed -- 8/8 is for 9/.357 and 6/8 typically .40/.45.

Trijicon HD sights are marked 226/225/228 or 229/220, but the difference is that the 229/220 front sight is .225, and the 226/228 is .215.

https://www.trijicon.com/na_en/produ...dns.php?mid=15

Update, they now label them 9/.357 and .40/.45 instead of the model numbers, which was nonsensical given 226 and 229 can be 9 or .40.

Yes, I flip-flopped them. That said, your last line is what I'm asking about. Why does caliber matter instead of model number? I don't understand why a 9mm would have one sight height, share it with a .357 Sig, but the .40 would have a different sight height.

[taadski]

Yes, I flip-flopped them. That said, your last line is what I'm asking about. Why does caliber matter instead of model number? I don't understand why a 9mm would have one sight height, share it with a .357 Sig, but the .40 would have a different sight height.

A heavier, slower moving bullet will spend more time in the barrel as it's lifting in recoil than a lighter, faster moving bullet, resulting in a higher point of impact.

[BehindBlueI's]

A heavier, slower moving bullet will spend more time in the barrel as it's lifting in recoil than a lighter, faster moving bullet, resulting in a higher point of impact.

Then barrel length should matter, too. If the time spent in the barrel between a 9mm and a .40 matters, why does it not matter if its out of a 3.3" or a 5" barrel?

[taadski]

Then barrel length should matter, too. If the time spent in the barrel between a 9mm and a .40 matters, why does it not matter if its out of a 3.3" or a 5" barrel?

Yep. Agreed. Lots of wheel gun guys talk about their 8" revolvers shooting noticeably higher than their shorter barreled guns using the same ammo. Much less significant difference with the Sigs though with only a 1/2" barrel length difference between the 225/228/229s and the 220/226s.


t

[TiroFijo]

A revolver has a very high bore axis, and is a rigid plattform. Vertical point of impact change due to different loads is quite marked, and depends on the load (recoil impulse and velocity), how you grip the gun, barrel length (barrel transit time), etc., so point of impact changes with user, specially with magnum loads. It is quite evident that the bullet exits the barrels while the gun is arching upward because when you zero the pistol at 25 yds the barrel is actually pointing downward.

With a pistol is different, the bore axis is much lower and the slide + barrel recoil together and soak up some recoil impulse, if you see hi slow motion films the pistol does not move upwards much until the slide hits the frame at the end of the recoil cycle. Also POI variations are smaller because most loads are pretty similar in recoil impulse to get reliable functioning (unlike revolvers where loads can vary a lot), and barrel lenght makes a smaller difference because 0.5" or even 1.0" do not add that much in barrel transit time since past 3.5" or so 90+ % of muzzle velocity is reached.

[MD7305]

My 1996 manufactured, duty 229 .40 had 8/8 sights. It shot dead on with a "drive the dot" sight picture at 25yds. I thought our guns might have initially been .357 guns then were converted to .40 with a barrel swap but they were triple serial number guns and all numbers matched. I've had other 229s in .40 and in PD inventory that had 6/8 sights and some shot "drive the dot" and some shot with a "6 o'clock hold" at 25yds. All of the newer 229s we got wore 6/8 sights but they were also Meprolights instead of the original Trijicons of the older guns. I'd go with what the sight maker lists for caliber but nothing's every guaranteed. I've seen POI/POA differences even using the same pair of sights on two different Glock 22. Who knows? You might contact Sig and see if they make or have access to 9/7 sights?

[taadski]

I'm personally not a huge fan of the whole "drive the dot" thing that Sig endorses and wind up making adjustments to get them back to a "tip of the front sight" type sight picture. Fortunately there are a few companies that have stepped up and manufacture an assortment of quality solutions.

BehindBluel's, here's a list of stock heights, if that helps you any. Just note some companies (like Trijicon) reference the entire overall height (that includes the dovetail portion like below) and some do not so you'll have to take that into account.

Sig factory:
*Note- the dimensions below include the entire height with the dovetail. NOT the blade only.

Rear sight heights:

#4 = 5.24mm (0.21 inches)
#5 = 5.52mm (0.22 inches)
#6 = 5.80mm (0.23 inches)
#7 = 6.07mm (0.24 inches)
#8 = 6.35mm (0.25 inches)
#9 = 6.62mm (0.26 inches)
#10 = 6.90mm (0.27 inches)

Front Sight Heights:

#5 = 6.01mm (0.235 inches)
#6 = 5.88mm (0.230 inches)
#7 = 5.74mm (0.225 inches)
#8 = 5.60mm (0.220 inches)
#9 = 5.46mm (0.215 inches)
#10 = 5.32mm (0.210 inches)




t

[BehindBlueI's]

My 1996 manufactured, duty 229 .40 had 8/8 sights. It shot dead on with a "drive the dot" sight picture at 25yds. I thought our guns might have initially been .357 guns then were converted to .40 with a barrel swap but they were triple serial number guns and all numbers matched. I've had other 229s in .40 and in PD inventory that had 6/8 sights and some shot "drive the dot" and some shot with a "6 o'clock hold" at 25yds. All of the newer 229s we got wore 6/8 sights but they were also Meprolights instead of the original Trijicons of the older guns. I'd go with what the sight maker lists for caliber but nothing's every guaranteed. I've seen POI/POA differences even using the same pair of sights on two different Glock 22. Who knows? You might contact Sig and see if they make or have access to 9/7 sights?

I e-mailed Trijicon and explained the "this is what it currently has, this is what caliber it originally was, this is the caliber I normally shoot" and will see what they say.