One of the many changes to infantry weaponry since September 11, 2001 has been the widespread adoption of several devices for infantry weapons. The most popular item is the red dot reflex site for rifles and machine-guns. This sight, similar to the point-and-shoot viewfinder found in cameras for many years, was first used by the military (U.S. Army Special Forces) in 1970, and also became popular with hunters and paint ball gun users. The red dot sight was more accurate than iron sights, could be used with both eyes open and was generally more effective at typical combat ranges (under a hundred meters). The sight was particularly effective at night, and in the 1970s, that was its big advantage.
Current devices, like the U.S. Marine Corps ACOG (Advanced Combat Optical Gunsight), does not use batteries and provides a red chevron-shaped reticle and bullet drop compensator. For daytime use, a fiber optic system collects available light for brightness and controlled contrast in the scope. At night, the system relies on tritium for illumination. The 4x32 sight allows you to get first round hits at 300 meter, or longer ranges. The sight still allows for better accuracy at closer ranges, with both eyes open. The manufacturer, Trijicon, made the original sights of this type back in the 1970s. SOCOM has long used them, and many marines and soldiers have bought the civilian version of the ACOG with their own money. At a thousand bucks each, ACOG costs more than the rifle it’s mounted on, and the users consider it well worth the price.
A Chinese firm manufactures a version of the ACOG sight, but violates the American manufacturers patents to do so. The Chinese version sells for as little as half what the legal version sells for.
In Iraq, American infantry widely used a wide variety of light, visible and invisible, to control the battlefield at night, and during the day as well. The simplest, and cheapest, light source was the Surefire White Light 6P. This small, $65 item puts out a bright, white light that not only quickly illuminates enemy troops, but also blinds them. This flashlight shaped device was initially attached to the end of a rifle with tape. This flashlight is a police item, as are many items the troops are getting for combat in urban areas. A lighting device for purely military use is also available.
These flashlights were useful because, when going inside buildings or caves, night vision devices don't work very well. That's because these gadgets just intensify available light. If there is no available light, there's nothing to intensify. So small flashlights are attached to the end of rifles when going into these pitch-black places. These are not your ordinary flashlights, but "white light" models. The white light is more likely to temporarily blind anyone who gets a good look at it, and spoil their aim if they start shooting at the source of the light.
But now the U.S. Army has a better device for this sort of thing, the MFAL (Multi-Functional Aiming Lights). This looks like a small flashlight, and attaches to the rifle. But this device can put out visible, or invisible (infrared, or IR) light. When using IR, you go into a cave providing light only you can see, with your night vision equipment. If you are real quiet (or sort of quiet), you have a big advantage over the bad guys trying to hide in the dark. This rig also allows you to see any booby traps the enemy may have laid for you. MFAL also emits a laser pointer (like the older "red dot"), but one that cannot be seen by the enemy (unless they also have night vision gear, which they usually don't.) The MFAL was developed with the help of feedback from combat troops in Iraq and Afghanistan.
Mounted on the rifle like a scope, the Integrated Laser White Light Pointer (ILWLP) provides an infrared aiming light out to 600 meters, and an infrared illuminator that will be good for 300-600 meters depending on how much moonlight is available. The infrared illuminator will also be able to light up an interior space of about 400 square feet. For the infrared illuminator, you need infrared lenses on your goggles to see what the infrared light illuminates. A red dot laser is also built into the unit and has a range of 10-25 meters, depending on the lighting conditions. There is also a white light (flashlight) capability, that can allows facial recognition out to 25 meters. Naturally, the ILWLP costs more than ten times as much as the Surefire White Light.
A more low tech, but equally useful item, is the dust proof magazine. A big problem with the M-16 type rifle is that the fine sand and dust found in Iraq and Afghanistan can slip past the magazine and into the magazine well, and lead to a malfunction. So commercial firms have come out with several generations of magazines that try to seal the magazine well to keep the talcum powder like crud out of the rifle. The latest of these is the Advanced Reliability Combat magazine, that includes a soft gasket that creates a dust proof seal when the magazine is inserted in an M-4, or similar weapon (like the SOCOM SCAR). These magazines cost $30 each (about 70 percent more than a standard magazine.) Magazines of this type are also available with another simple, but life-saving, innovation, a strip of see-through plastic running the length of the magazine, showing how many bullets you have left.
All these devices turn an M-16 or M-4 into a much more lethal weapon, and troops were buying a lot of this stuff with their own money, before the army and marines made most of these items standard issue.