Open Iron Sights provide horizontal and vertical reference points that allow the shooter to train the weapon. With typical blade iron sights, the shooter should center the front post in the notch of the rear sight and the tops of both sights should be level. Since the eye is only capable of focusing on one plane, and the rear sight, front sight, and target are all in separate planes, only one of those three planes can be in focus. The front sight should be in focus. Target shooters generally prefer a matte black finish to their sights, to reduce the chance of glare and increase the contrast between
the sights and the light bars seen on either side of the front sight. , Black sights don't offer good visibility with dark targets or in low light conditions, such as in hunting, military, or self-defense situations.
There are a number of different types of iron sights. Each manufacturer's sight can have different methods of aligning Point of Aim (POA) and Point Of Impact (POI). Adjustable sights allow the individual users to adjust the sights to their preferences as shown in the Bullseye Sights below, which provides a very distinct POA for maximum precision on specific size targets.
Various methods of open sight contrast enhancement. Left to right: Three dot, white outline, Straight-eight, red insert, dot and bar, gold bead and other variations..
Three-dot: On semi-automatic handguns, the most common type of enhancement is a bright white dot painted on the front sight near the top of the blade, and a dot on each side of the rear sight notch. In low lighting conditions the front sight dot is centered horizontally between the rear sight dots, with the target placed above the middle (front) dot. Some sight vendors offer differently colored dots for the front and rear sights.
White outline rear: A contrast variation which uses a dot front sight with a thick and bright white outline around the rear sight notch.
Straight Eight: Heinie Specialty Products produces a variant of high visibility sights in which a single dot front sight and a rear notch with a dot below can be lined up vertically to form a figure "eight".
Sight inserts: Popular on revolvers, this enhancement consists of a colored plastic insert in the front sight blade, usually red or orange in color.
Bar/Dot or Express sight: Similar to the Straight Eight type, this type of sight is also found on some handguns. The open, V-shaped rear allows for faster acquisition and wider field of view, though less accurate for longer range precision type shooting. The dot on the front sight is aligned or set directly above the vertical bar on the rear sight, commonly referred to as "Dotting the 'I'".
Night sights: On S.D. & tactical firearms, the contrast enhancements can consist of tubes containing tritium gas, which emit a dim light due to the radioactive decay of the tritium, and fluorescent material. Self-luminous tritium sights provide vital visibility in extremely low light situations where normal sights would be degraded or even useless. The tritium glow is not noticeable in bright conditions such as during daylight however. As a result, some manufacturers have started to integrate fiber optic sights with tritium vials to provide bright, high-contrast firearms sights in both bright and dim conditions.
Fiber optic: This method is most commonly used in front sights, but many makers offer sights that use fiber optics on front and rear sights. Fiber optic sights can now be found on handguns, rifles, and shotguns, both as aftermarket accessories and a growing number of factory guns. A fiber optic front sight is used by many competitors in action shooting competitions.
There are others that generally fit into one of these general types.
SIGHT ALIGNMENT:
As mentioned in the first paragraph, typical simple iron sight alignment centers the front post in the notch of the rear sight and the tops of both sights should be level with the desired POI. With various CONTRAST SIGHTS, this can vary quite a bit from different handgun/sight manufacturers. This can lead to some questions from users with different target options than the sights were designed to hit fast and accurately.
EXAMPLE: 3-DOT Sig Sauer pistol sights are usually aligned by lining up the three dots and placing the center dot ON the desired POI.
http://www.sigsauer.com/CustomerService/Faq.aspxIf the tops of the sights are lined up at the "desired" POI, the "actual" POI will be low. The 3-DOT variation shown in the first picture is typical of Sig sights and some others. Aligning the dots on the section of center mass that is for self defense or tactical target use is fast and accurate even in low-light situations. With very small targets or at greater ranges the 3-Dot sights may completely hide the intended target. This is where target sights can still be effective when enough light is present.
A number of questions about iron sights and their use reappear periodically. This attempts to show how different sights require different methods to hit the same bullseye.
Sources for information are compiled from various said-to-be reputable sources on line. Errors are my fault.
Holographic, closed iron sights and various scopes won?t be covered here.
Suggestions for changing, correcting or adding to this HANDGUN OPEN IRON SIGHT thread are welcomed.
