I put new Trijicon HD night sights on my Sig P226 and when I took her to the range, my grouping ended up being 6"s low at 7 yards. I would guess that I need a shorter front sight on the gun, but the kicker is that I have the exact sights on my P228 which shoots to point of aim with the exact same hold.

What am I over thinking or under thinking ??

Just two quick thoughts:
Years ago I would go to the range to shoot some and I would shoot low. My problem was I was anticipating recoil and pushing the muzzle forward and down. This is real easy to do. It is sometimes difficult to release the trigger when the front site is on the bulls eye.

Get someone else to shoot that 226 for you. If the sights are ok I bet they will be close to the bullseye.

I've been shooting for 40+ years. And I have the same sights on 2 other guns, one of them also a Sig. No problem with the other 2 guns, using a similar hold.

More info ... the sights I put on the gun, #600571 claim to be compatible with #8 Front and #8 Rear. For Sig Sauer 9mm and .357 Sig.

I'm not familiar with the markings on the the Trijicon HD sights. However, do the actual markings on the P226 sights (and the product ID) match the P228 HD's? regardless, do they appear to have the same dimensions? Wondering if the product was inaccurately labeled. Per Trijicon, I believe the same sight is used on both P228 and P226 pistols.

Did the P226 shoot to POA with the sights you replaced? What caliber is it? The 8/8 Sig OEM would indicate 9mm P226.

Does the P226 have the same grips used when you had the old sights installed? I've found a difference with POA/POI with my own P226 when using the original E2 grips versus the currently installed G10's.

An officer recently asked to replace the front sight of a P220 with a Trijicon HD sight, and he experienced much the same problem. The issue was of course that the replacement sight was very much taller than the original. The Trijicon HD set of front and rear has a high rear sight (something I was unaware of), so if you replaced both sights I wonder if somehow the rear wasn’t the proper one to use with the tall front.

The simple fact is that if the gun wasn’t shooting such a radical distance below the point of aim at 7 yards before the sights were replaced, that should be a clue about what is going on. Even if you never fired the gun before replacing the sights, it’s extremely unlikely that the gun itself is responsible. A POA/POI discrepancy of 6 inches at 7 yards is a huge amount. If there was an issue with how the barrel was locking up, I would expect the POI to be high, not low.

And this thread is a nice reminder to anyone reporting a problem that the more information provided at the beginning, the more likely the responses will apply to the actual situation. Most of the time when someone reports hitting extremely low at short distances it’s due to shooter error. Without knowing anything about the shooter’s prior experience with similar guns, it’s natural to assume that that might be the cause. Members on this forum have a vast amount of knowledge and experience, but I have yet to learn of one who can read the minds of people whom they’ve never met.

I'm going to bring both the 226, and 228 to my shop Monday to measure sight height with a caliper and examine the markings on the sights under magnification.

I'll let you know what I see and find out.

OK. I'm more confused than ever. I checked my new sights and it appears I have a $8, rear and a #8 front. My old sights are a #8 rear and a #8 front. The only thing is that my P228 front sights are 3mm wide and the P 226 front sights are 3.5 mm wide.

At this point in time, I'm starting to question myself all around. I need to get back to the range.

Use a set of calipers and measure the height of the rear sight to compare. The number markings may be incorrect.

wonder how your sights are working out. Same setup I went with my duty 226 in 9mm. Still dialing it in myself. thanks