Muffled by thick walls and layers of bullet-resistant glass, the sound of a high-velocity bullet striking MSA's advanced combat helmet was reduced to a soft pop.

A video camera recorded the effects and Doppler radar measured the speed.

It was just one of thousands of metal projectiles material scientists, engineers and technicians at the company's John T. Ryan Memorial Laboratory in Cranberry have been firing at helmets, and more recently, bulletproof vests.

A maker of safety equipment for 91 years, MSA has modified its military helmet and introduced a new line of protective gear for law-enforcement customers. The products were designed and developed at the Cranberry lab, where they are now being tested.

"Body armor is a natural progression," John Raimondi said during a recent interview at the lab. "We have a ballistics lab, ballistics experts and Ph.D-level materials scientists in house. A move [into making more police products] makes sense and is consistent with what has been our sole business: to protect people at work." Mr. Raimondi is product line manager for ballistic vests.

The modified helmets and bulletproof vests both are marketed under the company's ForceField brand.

Development of a civilian helmet evolved from the company's experience making Army headgear.

MSA's helmets are made from multiple layers of strong, tightly woven DuPont Kevlar. It is a synthetic fabric that can stop metal fragments the size of a pencil point and absorb the shock of much larger projectiles like bullets, according to company spokesman Mark Deasy.

Both the military and civilian models contain moveable comfort pads instead of webbing, and can be used with accessories like gas masks and night-vision goggles. Both permit installation of communications systems -- microphones and headphones -- into the helmets.

U.S. troops serving in Iraq and Afghanistan have been wearing the company's advanced combat helmet as standard issue for several years, and they have given the product good reviews. Many of those soldiers in Reserve or National Guard units work as police officers, sheriff's deputies or in other law-enforcement jobs.

"When those ex-soldiers return to civilian jobs, they want to have the same helmets they wore in the service," Mr. Raimondi said. Adapting the helmets for police use has meant re-engineering them to meet new problems.

The standard military helmet has been designed to withstand both small, fast-moving metal shards, like those produced by roadside bombs, and slower, but larger projectiles up to the size of a 9 mm bullet. The law-enforcement version has been adapted to provide protection from an even bigger .44-caliber Magnum bullet.

Weighing a little more than one-half ounce, a .44-caliber slug is more than 100 times the weight of some of the small, but potentially lethal, bits of shrapnel produced by the improvised explosive devices that make life so dangerous for U.S. troops in the Middle East.

Body armor, too, seemed like a natural extension of the company's product line, according to MSA's government products manager Hal Kersteen.

The computer-aided design, construction and testing of three armor prototypes was done at the Cranberry lab. MSA has contracted with a U.S. company to manufacture the finished product. Each vest will sell for between $700 and $2,500, depending on the amount of customizing and number of accessories. The company estimates the U.S. market for body armor at about $140 million per year.

Founded in Pittsburgh in 1914 as Mine Safety Appliances Co., the company's first products were electric safety lamps for miners. Since the lights did not produce an open flame, they cut the danger of mine explosions and fires. Over the decades, other MSA products have measured air quality, protected miners from noxious gases and provided emergency oxygen.

More recently the company has expanded its product line to include thermal imaging cameras, safety harnesses, safety glasses, ear protection and multipurpose, multisubstance gas detectors.

As a result, less than 5 percent of the company's $850 million in annual sales will come from the mining-related products that gave MSA its name.

The company's law enforcement products already include some of the thermal-imaging cameras, air-purifying respirators, and the MICH system, the "modular integrated communication helmet." It has a microphone and earphones that allow soldiers and police to communicate during combat or emergencies.

MSA has entered the market as one of nation's major producers of body armor is facing legal and financial problems over the safety of its bulletproof vests. The office of Pennsylvania's attorney general has sued Michigan-based Second Chance Body Armor, claiming the company failed to reveal information about rapid deterioration of the material from which its vests were made. Tests showed that exposure to light, heat and water all dangerously weakened the Zylon fibers used in the body armor.

ForceField helmets and vests are made without Zylon.

MSA's new products were unveiled at the International Association of Chiefs of Police conference in Miami last month. More than 14,000 delegates met with about 800 vendors at the Miami Beach Convention Center.

"Every police chief I know wants his officers to always wear body armor while on the job," said Ernie Batista. ForceField vests offer both more comfort and more consistent protection, he said. A former head of the Pittsburgh office of the federal Drug Enforcement Agency, Mr. Batista is MSA's Homeland Security market manager.

Mr. Kersteen and Mr. Raimondi demonstrated what they see as some of the main advantages of ForceField body armor over more traditional designs.

Two of the three MSA models, Alpha and Bravo, are worn under uniforms or street clothes.

The Alpha model has a built-in T-shirt made of a fabric that wicks away perspiration and has been treated with antimicrobial substance to control odors. It also contains sealed panels filled with phase-change materials that turn from solids to liquids, drawing heat away from the wearer's body.

The vests are equipped with "armor latch" closures. MSA's patent-pending design allows the wearer to pull forward on elastic flaps to secure the sides of the vest -- a more natural motion -- but still aligns the Kevlar or Honeywell GoldFlex panels in a front-over-back pattern. That arrangement reduces the opportunity for a bullet or metal fragment to burrow between the panels.

The Tango model is meant to be worn over clothing by SWAT teams or tactical squads.

MSA employs about 100 people at the Ryan research center and another 400 at its nearby instrument division. The company has about 1,600 employees throughout southwestern Pennsylvania and 2,400 throughout North America. Its world-wide workforce is 4,600.

Because the body armor will be made for MSA by another company, it is not expected to affect employment.

All progress comes with a price, and the use of 21st century materials in making helmets does bring an end to one traditional field practice.

The "steel pot" familiar to generations of World War II, Korea and Vietnam veterans did have one advantage over the advanced combat helmet.

MSA maintains a small museum of safety helmets, miners lamps, oxygen generators, breathing devices and gas masks at the Ryan laboratory, and that collection includes one of the old steel Army helmets.

Mr. Kersteen took it down from a display shelf and, turning it over, showed how a soldier's helmet could serve as a makeshift cooking pot.

While the new helmets are a lot better at stopping tiny shrapnel and high-speed bullets, he said, you can no longer cook in them.