However, they are not as good for making precise shots, especially at distance. Precise horizontal alignment requires having the center of the Big Dot aligned with the post, while precise vertical alignment requires having the Big Dot exactly on top of the post. At longer range distances, one needs to hold the top of the edge of the round Big Dot at the target. This is not simple and certainly not done quickly.
From the picture above, one can also see that the Big Dot is obscuring a significant part of the target at close range distances. This is true at longer range distances as well (50+ yards), as bullet drop and hold over come into play.
There is a reason why most modern handgun sights are notch and post. The human brain can easily line up right angles and rectangular objects. XS Big Dot sights do not follow this simple principle as they originate with big game hunters in Africa.
On the other hand, many modern handgun sights have markings on the left and right side of the rear notch that are too big, too bright and at the wrong place, such as the classic three-dot sights. Front sight focus is impeded if the rear notch markings are too big and too bright, as the eyes will naturally focus on the rear. Three-dot sights, or similar markings, also create problems for people with astigmatism, like me. Which of the four big white dots from the rear sight should I line up with the single small white dot from the front sight that I just acquired?
The solution is a combination of both, notch and post sights with rectangular angles, a highly visible front sight and a bar underneath the rear notch. There are a number of manufacturers producing such sights. Meet the Ameriglo CAP sights that I am using:
They are very good for taking fast shots at close range distances as they function like the XS Big Dot sights. They are also very good for making precise shots, especially at distance, as they function like traditional notch and post sights. The big rectangular front sight can be easily acquired, while the bar under the rear notch helps with less precise alignment for close range distances. The fact that the front sight has a rectangular coloring helps with the alignment of the rear notch for making precise shots.
For Glocks, I highly recommend the narrower front post sight. I have these sights now on my Glock 19, Glock 26 and S&W Shield 9mm. I am waiting for the delivery of the sights for my Glock 20. I have shot with these sights now for the past 4 weeks, 300-400 rounds per weekend. I am simply better with them.
The front sight has Tritium in it, while the bar in the rear sight has not. For those with proper training, that is not a significant issue. The rear sight has a good edge for one-handed operation.
Source: USA Carry