Believe it or not, many cops are walking around with the decaying remnants of America's nuclear arsenal strapped to their hips. After reading that sentence, I'm sure some of you are scratching your heads and thinking, "It's really time for that guy to retire."

But let me explain. The subject of this article is night gun sights, sometimes called "tritium" sights. Tritium is a radioactive gas that the United States has not produced since 1988 and all the tritium in the U.S. is now produced from dismantled nuclear weapons. So, if you have night sights on your duty gun or off-duty sidearm or both, you're carrying around a little piece of the nation's Cold War nuclear arsenal.

OK. Don't panic. Your tritium gun sights are indeed radioactive, but they present no danger to you or anyone else, well...unless you use them to put lead on target. The beta radiation given off by tritium is very weak. It won't penetrate human skin. It won't even pass through a piece of tissue paper.

Tritium is a radioactive isotope of hydrogen that typically is produced in nuclear reactors or high-energy accelerators. Because tritium is radioactive, it emits electrons at a specific rate, called a "decay rate." For tritium, the decay rate is about 5 percent per year, meaning that the radioactivity of the isotope has a half-life of about 10 to 12 years.

Yes, I know, this is not a nuclear physics lesson. But all this stuff about decay rates is important because it determines the life of your night sight. Let me explain. In a tritium night sight, tritium gas is captured in a glass tube, which is coated with phosphors just like on a TV tube. When the tritium releases beta rays, they excite the phosphors and that's what glows, not the tritium. This means that as the tritium loses energy, the night sight will become dimmer.

Remember, the half-life of tritium is 10 to 12 years and it dissipates its glow by about 5 percent per year. So in about five or six years, the glow will fade, making the efficiency of the sights considerably less than optimal. When you understand the physics, it becomes evident that you need to replace your tritium sights about every five years. And you should know this before you buy them.

But you should still buy them. More than 66 percent (that's two-thirds) of law enforcement shootings take place in low-light environments. That's a good reason to have night sights and once you have them, it's a good reason to change them out when they grow dim. Most manufacturers of night sights will replace the tritium inserts for a nominal fee.

Here's a quick look at the tritium night sight market.

AmeriGlo

Atlanta-based AmeriGlo produces a comprehensive line of tritium sights for Glock and Beretta handguns and for HK rifles, carbines, and subguns. All AmeriGlo night sights feature the company's trademark Betalight tritium lamps that are secured in a white PVC sleeve designed to provide the shooter with permanent white daylight rings and they all carry a 12-year warranty on the illumination.

AmeriGlo's Classic night sights are machined from steel for durability. These low-profile sights are also great for one-hand clearance drills, and they present you with an excellent sight picture in bright or low-light conditions.

With their sleek snag-free design, AmeriGlo's Smooth Slope night sights are great for concealed carry or tactical use. The rear sight is secured with twin clamping screws and is field adjustable for windage. The front sight installs easily with the included nut wrench. Smooth Slope sights come with tools because they are engineered for do-it-yourself installation.

For us older "seasoned" officers AmeriGlo also offers Ghost Ring sights. These are especially useful if you wear bifocal or progressive focus glasses. When looking through a ghost ring-style sight, the eye will naturally center the front post or front dot in the center of the ring. The ring has two smaller tritium dots at just the right aiming point for fast target acquisition.

Meprolight

Israel's Meprolight develops and manufactures a wide array of products for the military, law enforcement, and civilian markets. The company's products include electro-optical and optical sights and devices, night sights, and marking devices based on tritium technology, as well as security and military products based on LED technology.

As you might suspect, Meprolight develops and produces its products in close cooperation with military and law enforcement agencies around the world and, in particular, within Israel. The company is considered Israel's development and upgrade workshop for a wide variety of tactical products.

Meprolight makes fixed and adjustable sights for just about any handgun used by law enforcement today and for rifles, carbines, and shotguns. One interesting feature of all Meprolight sights is that the front sights are purposely brighter than their rear sights. This encourages the shooter to focus on the front sight and beyond. Two color combinations are also available such as a standard green front and an orange rear set. This can prevent errant alignment in extreme low-light situations.

Kimber America is the exclusive distributor of Meprolight products in the United States.

Trijicon

The name, "Trijicon," is almost as synonymous with night sights as "Coke" is with cola drinks. Wixom, Mich.-based Trijicon was a pioneer in the design and use of battery-free, tritium-illuminated scopes and sights, and it makes sights for numerous weapons.

Trijicon and its founder, Glyn Bindon, hold several U.S. and international patents on night sights. Unfortunately, Bindon was killed last September when his small plane crashed near Palmer, Alaska. Bindon was a true icon of the shooting industry and will be greatly missed.

Bindon's involvement with night sights began in 1980 when he went home to his native South Africa to visit an old friend. The friend showed Bindon a luminous gunsight he developed and hoped to sell. Bindon brought several samples back to the United States and eventually sold two. Soon after that another six sights quickly sold, then another 12 were ordered, and Bindon knew he had something. He started a side business out of his home, setting up his office in the family room. From that humble start, he built the multi-million dollar business know today as Trijicon.

Trijicon sights are not just the first tritium weapons sights, they are among the best. The Trijicon design features a tritium glass lamp installed inside a small aluminum tube that is sealed with a polished synthetic sapphire crystal. The clarity of the sapphire helps transmit the light from the tritium lamp and concentrates the light from the phosphor into a distinct round dot. Three round dots on the sight provide shooters with accurate weapon alignment in low-light conditions when a target can be distinguished.

In addition to being easy to see in all conditions, Trijicon sights are also very durable. The sapphire that seals the sight tube is extremely rugged (second to diamond in mineral hardness), and the entire assembly is shock mounted in silicone to protect the glass tube from recoil.[PAGEBREAK]TRUGLO

Dallas-based TRUGLO is best known for its fiber-optic sights, but it also makes tritium sights and a new line of TFO (tritium fiber-optic) sights. The TFO sight is available for selected Glock, SiG, HK, Kimber, and Springfield handguns.

This is a truly innovative product. The TFO sight's fiber optics provide superior bright-light performance. During the day, the sight really jumps out and provides the shooter with an outstanding sight picture. In low light, the fiber optics seem to amplify the available light, and with the tritium as a "kicker," the sights are easy to see and automatically draw the eye. At night, the combination of the two systems gives you an exceptional sight picture. Most people who shoot using these sights think the illumination is battery powered.

21st Century Technologies

Innovative Weaponry Inc. (IWI), a subsidiary of 21st Century Technologies, is one of the leading manufacturers of night sights. The company has contracts with some of the largest gun manufacturers and has installed its P-T (Practical-Tactical) Night Sights on weapons of federal law enforcement teams and on the weapons of U.S. military spec ops units, including the ones that don't officially exist.

IWI's P-T Night Sight is a fixed system that is extremely robust. It is machined from bar stock steel and designed with the front sight brighter than the rear sights since the key to acquiring a target in low light is the ability to locate the front sight quickly and accurately.

P-T Sights come in a variety of colors. The front sight is always green, but the rear sight is available in orange, yellow, blue, green, or red.

Miniature Machine Corp. (MMC) is another subsidiary of 21st Century Technologies that makes night sights. The MMC sights are similar to IWI's P-T Night Sights, but with one pretty significant difference: MMC sights are adjustable. If you are not shooting point of impact, point of aim because of your eyes, eye dominance, or technique, or if you frequently change the ammunition you shoot, you really need to consider what adjustable sights can do for your shooting.

MMC sights carry a lifetime guarantee on workmanship and materials. The tritium tubes contained in the MMC sights are produced by IWI and warranted for 15 years. The standard finish is a fine black oxide, but MMC night sights are also available in Teflon-coated and stainless steel/Teflon-coated finishes.

XS Sight Systems

Fort Worth, Texas-based XS Sight Systems makes the 24/7 Express Big Dot Tritium System, the sight system I have on my duty gun, my off-duty gun, my home defense pistol, and my home defense shotgun.

I first used the XS Sights at the Gunsite Academy in Arizona. My eyes just aren't what they used to be, and I found that I was having real problems quickly picking up the front sight and the target. The 24/7 Express Big Dot Tritium System made that problem disappear.

The philosophy behind the XS system is nothing new; express sights have been around since the early 1800s. That's why many of the fine old double guns introduced by the English aristocracy in Africa to hunt lions or Cape buffalo and other highly dangerous game were equipped with express-type sights characterized by a rear blade in a shallow V design and a front sight consisting of a fairly large ivory or gold bead. When you have 2,500 pounds of evil attitude and horns or 1,500 pounds of claws and really big teeth charging you there is no luxury of acquiring a fine-precision sight picture. The same is true when some street punk is drawing on you in a dimly lit alley.

That's why the XS 24/7 sight features a modern variation of the tried-and-true express sight design. The rear blade on the 24/7 is a shallow V design with a small vertical tritium post. The front sight is a large precision white dot with a tritium tube in the center.

The benefits of this system are startling. It is the fastest gun-fighting, self-defense sight system I have ever used in both daylight and low-light conditions. With little practice, my speed improved by half and I continued to be accurate from the up-close gun confrontation distances all the way back to more than 25 yards. All you have to do to acquire the target with the 24/7 is simply line up the stick on the rear sight with the dot on the front.

The 24/7 Express Big Dot Tritium System is available for more than 20 different makes of handgun. XS also makes a great system for the AR series and for HK carbines, and its ghost ring shotgun sights will enhance any tactical shotgun.

AmeriGlo
www.ameriglo.net

Meprolight
www.meprolight.com

Trijicon
www.trijicon-inc.com

TRUGLO
www.truglosights.com

21st Century Technologies
www.ptnightsights.com
www.mmcsight.com

XS Sight Systems
www.expresssights.com

Sgt. Dave Douglas is the rangemaster of the San Diego Police Department and a Police magazine contributing editor.