Interview: Phil Seberger

Silencer 101

by Cameron Hopkins

July, 2000

 

Forget what you’ve seen on TV or read in The Poor Man’s James Bond- the facts about sound suppressors will surprise you.

We’ll start today’s lesson on silencers with a pop quiz. True or false. Adding a silencer to a rifle increases the rifle’s accuracy. The answer is true — if you’re talking about a remarkable sound suppressor or “can” from Phil Seberger of OPS Inc.

In a demonstration of Seberger’s 3rd Model M24 MBS (Muzzle Break Suppressor), I witnessed a Remington 700PSS in 308 fire two consecutive five-shot groups at 100 yards, using Black Hills excellent 168 gr. moly-coated match ammo, with and without silencer. The suppressed group was .220″ tighter.

True or false: Adding a silencer to a rifle increases the muzzle velocity. Again, the answer is true. In another demonstration, two 10-shot strings were fired over an Oehler 35P chronograph, with and without averaged 32 fps higher with the silencer than without.

While these answers may surprise you, it probably won’t come as much of a shock to learn that suppressors reduce felt recoil far better than most compensators or muzzle breaks. In fact, a silencer is nothing more than an incredibly efficient muzzle break.

An OPS Inc. silencer works by different principles than most silencers on the market that try to slow or trap the escaping gas. OPS Inc. cans work by capturing the sound waves of a gunshot as they exit the muzzle. Through a series of baffles inside the can the suppressors redirects the sound waves causing them to ricochet back into themselves canceling themselves. It’s called the “out of phase” principle of sound reduction.

Seberger, 76, explained the principle this way: “I got the bright idea that if I could go and hold the first sound pulse back in time, and insert it back when the second pulse came along, I’d have sound cancellation and I’d have nothing left but heat. I’d change the sound energy into heat energy. You can’t get rid of energy, you know.

“In a gunshot, the first positive pulse occurs as the sine wave goes up then down. It has considerably more amplitude than the negative pulse. We take that pulse and it dissipates a lot of energy as it hits the back of the chamber. What’s left will then be out of phase with the negative pulse, so they cancel each other out. They’re out of phase.”

Realizing that I was a bit glassy eyed from the technical explanation, Seberger translated it into something I could understand: eight ball. “The sound bounces back, just like a billiard ball. Then it is out of phase. It then meets the next wave and it cancels itself out,” the retired electrical engineer said.

The Physics Of Silence

Sound is a form of energy. When the propellant in the cartridge case burns from the primer’s ignition, the resulting energy propels the bullet down the barrel and causes the rifle to recoil. But there’s still some energy left. It takes the form of noise.

The law of the conservation of energy holds that energy can be neither created nor destroyed, only transformed. Thus, the idea of a silencer is to change the sound energy into heat energy Hiram Maxim, who invented the silencer in 1905, utilized this law, although he didn’t know it.

Maxim’s silencer came about after he watched water flush in a toilet and saw the water swirl. “If I can make sound swirl in a tube, it will make the sound go away,” thought the father of the machine gun. His silencer was crude and only marginally effective, but his “swirling water” theory stumbled on the fringe of the most efficient way for a suppressor to work — sound cancellation.

OPS Inc. silencers work by redirecting sound energy, if you will, in a series of very special baffles and chambers. The sound is bounced around inside the can colliding with itself where it essentially dissolves into nothingness, turning to heat in the process.

A suppressor gets hotter than the barrel after a few rounds. You can actually feel hot spots on a suppressor after only a couple of rounds, feeling where in the can most of the sound-to-heat transfer took place.

The Rolls Royce Of Cans

Seberger, a World War II veteran, manufactures the Rolls Royce of suppressors. Knowledgeable insiders in the most elite areas of the U.S. Special Operations community say that what sets the Seberger can apart from other makes is its incredible durability and performance.

In a government test at an undisclosed location, a Seberger 3rd Model MBS (Muzzle Brake Suppressor) was attached to a belt-fed .308 caliber M-21 HK machine gun. There are 100 rounds in a 7.62mm belt for an HK-21. Belts were linked together in 200-round sets. The military inspectors figured that the 12″ long, 28 oz. can might be good for a few belts — maybe.

Two hundred rounds of .308 through a machine gun is a hell of a test for a suppressor. They set up a special microphone attached to an audiometer to measure the sound. Temperature sensors were placed at various points on the weapon and the suppressor.

Targets were set out to record accuracy before and after the test. The HK-21 is an extremely accurate weapon when fired in semi-auto mode. Seven belts of 200 rounds each were fired as continuous bursts. The weapon was then allowed a cooling time of two minutes before the next belt of 200 rounds was fired.

The Seberger device registered 890 F and the shooter had to wear an asbestos glove to protect himself from the trigger, which reached close to 200 F. The government inspectors weren’t just impressed, they were amazed. They checked the audiometer — absolutely no degradation of the sound suppression or accuracy.

OPS Inc., Seberger’s company, received a substantial order for the $825 3rd Model can. That, by the way, is dirt cheap for what everyone agrees is the best suppressor on the market. A rival company sells a similar, albeit less durable and poorer quality unit for twice as much.

Why would Seberger virtually give away his design? “To me, the money isn’t important if I can save some guy’s life. I was in World War II. I know what it’s like when your friends don’t come home,” said the affable veteran of the European Theater.

“Phil sells his can as cheaply as he does because he wants the operators to have the best,” said Barry Dueck, a former Marine who conducts research and development testing for OPS Inc. “He never wants an agency to forgo his suppressor just because it doesn’t have the budget.”

If $825 is too much, how’s $750 for a 12th model or $575 for an M4 model? Still too rich? How’s free? During the Gulf War, Phil was contacted by a Marine from a very respected company in the Corps asking how many suppressors his unit could purchase for a stated amount. Phil responded, “How many do you need?”

The puzzled Marine tried to explain he had only X-funds allocated for silencers. Phil again responded, “How many do you need? No Marine is going into combat without a piece of needed gear due to funding limitations.” The Marines were sent all the suppressors they needed!

Building A Better Suppressor

Seberger’s cans come in two sizes: 5.56mm and .30 caliber. He is said to be developing a third for the .50 BMG caliber, but that is still in the skunk works of his northern California hideaway.

The MBS series of suppressors have been in use by U.S. Forces since 1988, seeing action in Panama, Iraq, Somalia and Haiti. “These silencers have seen combat duty all over the world. We’ve had over 90,000 rounds through individual silencers and we’ve never had a production failure. I don’t think anyone else can say that,” Seberger added. His strongest competitor is only getting 5,000 rounds before failure of their suppressors.

How exactly is a silencer made? The answer is, very carefully. There are 121 individual welds inside a 11″ long Seberger 12th Model 308 can with a series of baffles and chambers configured to create the “out of phase” effect.

Exactly how many baffles, how thick, in what location, Seberger ain’t telling. But you can find out if you want: just look up his patents. He has several, and they’re all still valid.

Seberger has built elaborate test equipment to measure the sound attenuation from his suppressor, duplicating the equipment capability at the government’s Aberdeen Proving Grounds. Starting with a very expensive Larson Davis microphone hooked to a Techtronics oscilloscope, Seberger rigged up a sound-measuring device that is so accurate, the device has to be calibrated to the electrical current that powers it.

With his better mousetrap, he proved his better soundtrap. Seberger achieved a 40dB reduction in sound, which, because the decibel measurement is logarithmic, means that the pfffft you hear is 1/100th that of the unmuffled gunshot.

By comparison, a World War II vintage silencer yielded only 15dB reduction, or 1/6th the original sound. These old cans were two feet long, compared to Sebergers modest 8.7″, of which 2.6″ is actually overlapping the barrel for an added length of only 6.1″ for the 12th Model 5.56 MBS. If you subtract 1″ for the standard flash hider, the MBS adds only 5.1″ to the weapon.

Do You Hear What I Hear?

Sound suppression is significantly enhanced with the use of sub-sonic ammunition. Standard ammunition in .223 and .308 clips along well over the speed of sound, roughly 1,118 fps at 59 F, hence there is a very noticeable “crack” from the sonic boom of the bullet breaking the sound barrier.

On a semi-auto, the noise of the bolt carrier clattering back and forth along with the gases exiting the ejection port is louder than the sound exiting the suppressor itself. Hence, the sonic crack of the bullet is much louder than any noise produced by the weapon’s operation.

With sub-sonic ammo, however, Seberger’s can is nearly inaudible. On a bolt action .308 you can hear the firing pin click on the primer and a light thud a moment later as the bullet punches through the target at 100 yards.

Along with greatly reducing the sound of a gunshot, a silencer also masks the orange flame of muzzle flash and eliminates the blown dust from muzzle blast, concealing the shooter’s location even further. Quieter, more accurate, less recoil, more velocity, less muzzle blast — that’s quite a list of attributes in a tactical situation.

And it’s an advantage Phil Seberger fully appreciates. When he joined the Army to fight Hitler, so did all of his buddies from his old Boy Scout troop. Only 75 percent of them came home. “War isn’t this deal with John Wayne. When you’re dead, you’re dead.”

Seberger paused, his memory swimming with images of his Boy Scout friends. I just don’t want good men to die because of bad equipment.”