Each baffle of the Impuls IIA suppressor indexes with a spacer (made from aluminum alloy in pistol caliber suppressors) using a tongue and groove arrangement possibly inspired by the tongue and groove indexing structures used in the cast baffles with integral spacers developed for the Vaime suppressors in Finland during the 1980s. The B&T design uses tongues on the front and back faces of the baffle base, which mate with grooves cut on each end of the spacers. This feature ensures that asymmetric structures on the baffles align properly for optimum performance.

The metallurgy used in the B&T designs is unusual. The baffles are now machined from an exotic steel alloy not available in the States. This steel has its atypical structural and harmonic properties because of the rather surprising elements that are added to the alloy. Originally, the baffles were machined from an esoteric aluminum alloy with an Inconel blast baffle, but HK (Oberndorf) wanted a suppressor that would give a longer service life to the HK pistols than the original military requirement of 5,000 rounds. B&T changed the material used in the baffles, and redesigned the Nielsen Device for the new suppressor mass, producing a silencer that now gives a pistol and silencer service life of 10,000+ rounds.

What’s the actual lifespan of the suppressor itself? I don’t know of anyone who has tested one to destruction yet. One user has 14,000+ rounds through the system. The rearmost baffle sustained enough sandblasting by unburned powder and primer particulates after about 8,500 rounds that the user moved the rearmost baffle to just behind the front-most position. Since five of the suppressor’s six baffles can be rearranged, this implies a baffle life for the system of 5 x 8,500 = 42,500 rounds. Unpublished data from Europe suggest the suppressor tube should have a minimum lifespan of 15,000 to 20,000 rounds.

The suppressor tube is made from an exotic aluminum alloy not available in the States, and it requires a proprietary heat treatment to provide an unusual mix of strength and elasticity. It appears that, if either the baffles or the suppressor tube were made with the aluminum and steel alloys commonly used in the U.S. firearms industry, these components would experience structural failure. The lifespan of the tube might be increased dramatically by reheating the tube to the aforementioned proprietary temperature to “normalize” the work-hardened alloy every 10,000 rounds (thereby removing the brittleness that slowly accumulates with use). This is an area that has received no research to date, however, and there would appear to be little financial incentive to conduct such a study.

Since the requisite steel and aluminum alloys are not available in the States, CCF/Swiss goes to the significant expense of air-freighting its tube stock and bar stock into the country from Switzerland to ensure the necessary durability of these critically engineered systems. CCF/Swiss manufactures these baffles to very close tolerances on a $0.312 million six-axis CNC indexing machine and the complex fluted structure requires considerable machine time per baffle.

The basic Impuls IIA suppressor is available for pistols in the following calibers: 9x19mm, .40 S&W, 10mm Auto, and .45 ACP. A variety of impulse or Nielsen devices are specifically engineered to the timing and force requirements of the following pistols: Heckler & Koch Mark 23, USP (Universal Self-Loading Pistol), and USP45 Tactical; Glock 17, 19, 20, 21, 26, 27, 29, 30; SIG 226, 228, 229; and SIG Pro. Nielsen Devices are also available for the 9x19mm and .40 S&W variants of HK’s USP Tactical Pistol, which are not available in the United States at this time.

As designed for the HK Mark 23 pistol, the Impuls IIA is 7.83 inches (19.9 cm) long and has a diameter of 1.38 inches (3.5 cm). With six proprietary steel baffles, the .45 caliber Impuls IIA weighs 14.9 ounces (421 grams). Steel components are finished in a matte black oxide, the aluminum spacers are anodized, and the suppressor tube, Nielsen tube and front-end cap are finished in a black hardcoat anodizing. The rear of the suppressor tube is knurled, as are the Nielsen Device tube (attached to the rear of the suppressor tube) and the rear end cap of the Nielsen Device, so the both the suppressor and impulse device can be fully disassembled for cleaning or servicing, although this is not required very often. At the insistence of HK (Oberndorf), B&T’s Nielsen Device incorporates the alignment indexing system developed at Knight’s Armament Company, although the different manufacturing techniques and specifications used to build the Impuls IIA make any such adjustments unnecessary.

Cleaning and Maintenance

While the Impuls IIA suppressor comes with a disassembly tool and manual, I do not recommend disassembly for routine cleaning and maintenance. After a shooting session, simply unscrew the rear end cap and remove the Nielsen Device piston with its captive spring. Place the suppressor with the rear end down in a metal tennis ball can or similar vessel filled with WD-40. Soak along with the rear end cap and piston for one hour. Drain and blow-dry with an air hose. No other routine maintenance should be required. If you have a Dillon CV-2001 Vibratory Case Cleaner, an acquaintance informs me that you can transform a pair of metal tennis ball cans into a poor-man’s ultrasonic suppressor cleaner in a few minutes. You’ll need a hole cutter for your electric drill sized to the cans, a board wider than a can and as long as the diameter of the vibratory cleaner’s lid, a roll of picture hanging wire, and some dry wall screws and screw eyes. Drill a can-sized hole in the middle of the board and then one on each side of that hole equidistant from the center hole. Remove the lid from the vibratory cleaner, and screw it onto the board with drywall screws so that the central hole gives clearance for the lid’s wing-knob. Set the cans in the two outlying cutouts in the board and secure with guy wires wrapped several times around the top of the cans (leaving enough room to fit the can lids), securing the guy wires to screw eyes appropriately spaced in the board. Buy a gallon can of WD-40, place suppressors in the cans and then fill with WD-40. While this may not be as effective as a $3,000 ultrasonic cleaner, it’s a whole lot better than a simple soaking on the workbench.

Performance

The milspec version of the Mark 23 (engraved “MK 23” on the slide) features a match-spec chamber, enabling it to deliver 2-3 inch groups at 50 yards using Black Hills 230 grain FMJ ammunition (with or without a CCF/Swiss Impulse IIA suppressor installed). The commercially available version of the Mark 23 pistol (engraved “Mark 23” on the slide) features a looser SAAMI-spec chamber, which might be a contributing factor as to why these pistols seem to deliver somewhat less accuracy than the milspec “MK 23” pistols. That said, the SAAMI-spec chambers make more sense for civilian end-users because they will digest a wider range of ammunition.

The Mark 23 barrel is threaded 16x1mm RH, while the barrel on its smaller sibling, the USP45 Tactical, is threaded 16x1mm LH. Left-hand threading was used by HK on the 9x19mm, .40 S&W and .45 ACP variants of the USP Tactical as a simple way for organizations or individuals fielding both the Mark 23 and USP45 Tactical pistols to avoid accidentally installing a recoil enhancement module designed for the Mark 23 on the smaller pistol, or vice versa. This is a consideration because the same Impuls IIA sound suppressor can be used for either the Mark 23 or USP45 Tactical pistol by changing the piston in the Nielsen Device. Simply swap out the piston with its captive spring for the piston required for a particular pistol. It’s easy to keep track of which piston goes with which gun. The piston without holes in its side is used with the Mark 23 (either the milspec or commercial variants), while the piston with large holes drilled in its side must be used with the USP45 Tactical.

To evaluate the performance of the sound suppressor, I tested CCF’s Impuls IIA on HK’s Mark 23 pistol and USP45 Tactical pistols using Black Hills 230 grain FMJ ammo (Black Hills Ammunition, Inc., Dept. SAR, P.O. Box 3090, Rapid City, SD 57709-3090; phone 605-348-5150; fax 605-348-9827; URL http://www.black-hills.com). The Impuls IIA can be used as a dry can for maximum convenience or as a wet can for maximum sound suppression. When using in wet mode, the Impuls IIA uses a tablespoon of water as the coolant medium. To add coolant, simply pour some water from your canteen into the rear of the Impuls IIA, shake a few times to distribute the water, and allow any excess to drain. This entire procedure takes about five seconds. Then mount the suppressor on the gun. The Impuls IIA will retain this water for about a day at moderate temperatures without shooting or for at least a full magazine of shooting.

The sound pressure levels of suppressed and unsuppressed pistols are reported as decibels in Table 1, and net sound reductions appear in Table 2. The Black Hills ammunition averaged 829 fps using the HK Mark 23 pistol and 821 fps using the HK USP45 Tactical pistol. All tests were conducted on the same day at a temperature of 72 °F. When fired dry, the Impuls IIA produced a mean (average) sound signature that was just above the pain threshold of 141 dB on the Mark 23, and just below the pain threshold on the USP45 Tactical. If maximum stealth or hearing protection is required, adding a bit of water to the rear of the can drops the mean sound signature by 11-13 decibels, which is a bunch when you recall that the decibel scale is logarithmic rather than linear. The CCF/Swiss Impuls IIA fired wet provided a net sound reduction of 29 dB on the Mark 23 and 30 dB on the USP45 Tactical.

This is very good performance. What the numbers don’t show is the butter-smooth operation of the CCF/Swiss Nielsen Device. It is perfectly tuned to the force and timing requirements of the Mark 23. When this smoothness of operation is combined with the fact that the suppressor eliminates about half of the perceived recoil, placing rapid follow-up shots is addictively easy. The elevated sights on the Mark 23 and the USP45 Tactical provide excellent sight pictures over the suppressor, so the speed of target acquisition and precision of shot placement are outstanding. Whether mounted on a Mark 23 or an HK USP45 Tactical pistol, the Impuls IIA from CCF/Swiss operates more smoothly than any Nielsen Device I’ve ever used on a .45 ACP sound suppressor. This makes me a better and a more confident shooter. The Nielsen Device is also very well designed to tolerate the grit and grime encountered during military operations in the real world.

It is also interesting to note that the Impuls IIA was quieter on the USP45 Tactical than the Mark 23. The fact the Impuls IIA was quieter on the pistol with the shorter barrel implies that the baffle design “likes” higher velocity gases. This, in turn, suggests that the suppressor might actually be more effective if it were redesigned to a smaller diameter so the asymmetric baffles could work the gases even harder.

Final Thoughts

It is safe to say that the Impuls IIA is a tough, user-friendly suppressor that provides acceptable sound suppression when fired dry and very good sound suppression when fired wet. If you count all caliber variants, the Impuls IIA is probably issued in greater numbers to elite military, security and law-enforcement units outside of the United States than any centerfire pistol suppressor in history. Thanks to CCF/Swiss Inc. (Dept. SAR, P.O. Box 29009, Richmond, VA 23242; phone 804-740-4926; fax 804-740-9599; URL http://www.ccfa.com), agencies and qualified individuals within the United States now can obtain this impressive technology for their own demanding applications. Mounting the CCF/Swiss Impuls IIA suppressor on the Mark 23 or USP45 Tactical pistol provides an accurate, quiet, and robust system that should satisfy both the armed professional and the qualified civilian.

Genius in Suppressor Design

The design of sound suppressors took a quantum jump forward on May 13, 1986, when the U.S. Patent Office awarded Patent Number 4588043 to Charles A. “Mickey” Finn. In my opinion, the three baffle designs covered by this patent represent the most significant achievement in sound suppression technology over the preceding three-quarters of a century. Not since Hiram P. Maxim’s Patent Number 916885 was awarded on March 30, 1909, had the field of silencer design seen such genius applied to the problem of stealthy shooting. Taking the time to understand how Finn’s innovative baffles work is a great way to jump well up the learning curve on how to effectively dampen the sound signatures of gunshots. In fact, one can make the argument that mastering the information in Finn’s patent will provide the moral equivalent of a Master’s Degree in sound suppression.

Much of the progress in the field of suppressor design throughout the late 1980s as well as the 1990s has been stimulated by analyzing the principals revealed by Finn’s work, and then applying those lessons in new ways. That, in a nutshell, is how progress in science and technology always works.

The easiest way to get your hands on Finn’s patent is to visit IBM’s Intellectual Property Network on the World Wide Web (the URL is http://www.patents.ibm.com). Once you’ve digested this patent, searching the database with key words such as “silencer” or “suppressor” or Boolean phrases such as “silencer + gun” or “suppressor + firearm” will reveal a number of additional patents worth studying if you are a serious student of suppressor design. Using a Boolean search phrase will help avoid a lot of extraneous hits related to automobile mufflers and silencers for air conditioners. But the cornerstone of such a quest for knowledge should be Finn’s ten-page Patent Number 4588043.

The patent describes three distinctly different baffle designs based upon a central concept—the slanted sidewall—which is defined as “a cylinder whose axis passes through the central axis of the sound suppressor at a predetermined angle so as to direct propulsion gases passing through the opening.” The slanted sidewall directs a gas jet diagonally across the gas stream following the bullet, deflecting a portion of that gas stream away from the central axis of the suppressor, where the gases can be slowed and cooled, robbing them of energy that would be perceived as sound. Four of the twelve figures in the patent are included here.

Figure 1 shows the preferred design of Finn’s Type 1 baffle (called the “first embodiment” in the patent, it has subsequently come to be known as the Type 1 baffle by suppressor cognoscenti). While this is a versatile design with a great deal of subtlety, it requires a fair amount of machining. I have seen simplified versions of the Type 1 baffle used for some applications. In fact, a photograph accompanying this discussion shows a Type 1 baffle simplified as much as possible; it’s just a flat disk with a slanted sidewall. Two noteworthy aspects of the preferred embodiment of the Type 1 baffle include the use of asymmetric surfaces to maximize turbulence and the use of geometry to enhance the effectiveness of the slanted sidewall. The Type 2 and Type 3 baffles also incorporate radial openings into the rear of the slanted sidewall (see Figures 2 and 3, respectively). These openings are designed to increase the diagonal gas jet formed by the slanted sidewall.

The preferred embodiment of the Type 3 baffle includes an integral conical spacer and a flat baffle. The baffle incorporates slots in the rear surface that communicate with an annular chamber inside the baffle. The annular chamber dumps gas into the rear of the slanted sidewall via three radial ports. A cut-off chord in the rear surface of the baffle (which is perpendicular to the aforementioned two slots) provides a large third pathway into the annular chamber inside the baffle.

The preferred embodiment of the Type 3 baffle also includes a mousehole at the wide part of the conical spacer (see Figure 4). This mousehole has several functions. It permits the flow of gasses from the coaxial expansion chamber (formed by the conical spacer) back into the central axis of the suppressor. And it releases gas pressure from the front of the coaxial chamber, which prevents the buildup of back pressure that would prevent more gas from entering the rear of the coaxial chamber.

While one can learn a great deal about the outstanding Type 3 baffle from the text and drawings of Finn’s patent, there is no substitute for seeing the actual object being described. Therefore, the photos accompanying this discussion provide details of the Type 3 baffle used in the Large Suppressor designed for the MP5SD-N. The Large Suppressor was manufactured by Heckler & Koch for the U.S. Navy under a licensing agreement from Qual-A-Tec in Oceanside, California. Heckler & Koch used a proportionately smaller but otherwise identical Type 3 baffle in the Small Suppressor, which was designed for the HK P9S pistol as well as the MP5-N and MP5K-N submachine guns. While the designs of HK’s Small and Large Suppressors are discussed in a two-part article that appeared in The Small Arms Review [see 2(4):28-32 and 2(5):28-31], photos illustrating the details of a Type 3 baffle as used by Heckler & Koch were not available at that time.

Note from the photos that the Type 3 baffle design used by Heckler & Koch moved the mousehole from the front edge (wide part) of the conical spacer to the rear (narrow part) of the conical spacer opposite the front edge of the slanted sidewall. Placing the mousehole here increases the efficiency of the slanted sidewall, directing its diagonal gas jet into the coaxial expansion chamber formed by the spacer.

Heckler and Koch began producing robust, accurate and quiet silencers based on Mickey Finn’s Type 3 baffle in 1986. The specific suppressor designs were developed by Finn’s company Qual-A-Tec and manufactured under at HK’s facilities at Chantilly and Sterling, Virginia. The photos of HK’s Small Suppressor accompanying this article were provided by Hays Parks, who was involved with the Navy’s development of an effective 9x19mm subsonic round in the 1980s based on a 147 grain projectile. The goal was to develop a 9x19mm cartridge that would provide an optimum mix of accuracy, incapacitation of the target, and lack of overpenetration. The latter criterion was important since the mission of certain elements within the Navy had been expanded to include in extremis missions such as counter-terrorism and hostage rescue. The HK P9S pistol and Small Suppressor were used during the course of this research program, which spawned the Winchester 147 grain JHP subsonic round that has stimulated the proliferation of 147 grain rounds in the marketplace.

The U.S. Navy is seldom seen as the originator of innovative developments in small-arms ammunition. But in the case of the 9x19mm JHP subsonic round, Navy innovation made a significant contribution not only to military technology, but to technology available to the law-enforcement community and private citizens as well. (The Navy’s development of this round is discussed at length in Silencer History and Performance, Volume 1; ISBN 0-87364-909-5). It is reasonable to assume that 147 grain JHP will play a major role wherever 9mm ammunition is used for decades to come. While the HK 9mm suppressors using Mickey Finn’s Type 3 baffle are now out of production, they remain in the Navy’s inventory, and they should provide service well into the future as well.

Most important of all, Mickey Finn’s innovative baffles and suppressor construction have fundamentally changed the field of silencer design. If one uses a yardstick based upon the number of practical and effective suppressors developed by other designers based directly or indirectly upon the principals revealed by a designer’s work, then one could make the case that Finn’s slanted sidewall baffles represent the most important contribution ever made to the field of sound suppressor design.

That may overstate the case only slightly, for Hiram P. Maxim provided the first commercially successful silencer designs, proving that gunshot noise could be reduced substantially by a simple, compact and practical device that could succeed in the marketplace. We might not be having this discussion at all without Maxim’s contributions. Furthermore, Maxim’s outstanding designs still work pretty well by modern standards even though they date back to the era of primitive canvas and wire biplanes.

When Finn turned his genius to suppressor design, the state of the art was not much different from World War II technology developed during the era of the radial engine. Finn’s work catapulted the field of suppressor design into the Space Age, providing a quantum jump in the state of the art and fundamentally changing the direction of subsequent developments. It is my contention that the contributions made by Hiram P. Maxim and Charles A. “Mickey” Finn to the field of suppressor design can best be described by the word “genius” since they have contributed “extraordinary creativity” to the field of suppressor design. That’s quite a legacy.

1997 Silencer Trials

Dateline: Knob Creek, KY, May 22, 1997. This day was an unprecedented event in the annals of small-arms history; almost all of the silencer manufacturers in the United States came together to have the performance of their sound suppressors tested side by side, using scientifically appropriate sound test equipment. This was very much a team effort with me supervising the tests, Dr. Phil Dater handling the Larson Davis Model 800-B sound meter with Larson Davis 2530-1133 1/4 inch random incidence microphone and automated data recording using a Hewlett-Packard OB-425 computer and software he developed for the purpose, and Dan Shea organizing the scheduling, volunteer shooters and the ammunition supply. We also used a Pact MK-IV Timer/Chronograph with MK-V skyscreens for recording projectile velocities.

I figured we had time to run 60 tests that day, but the demand for data was so intense that we somehow managed to squeeze in 163 test strings. We gathered as much data in a day as I normally produce in a year, giving all of the participants a chance to see how their products measured up to the competition in terms of hard numbers and subjective qualities such as tonality.

It’s hard to adequately express, much less overstate, my admiration for all of the participants since the complete spectrum of the industry was represented. Relatively new, one-man operations competed against well-established design teams of more well-known companies like Knight’s Armament and Gemtech, all competing on a level playing field. Some participants were pleasantly surprised by the performance of their products, while some discovered that individual products needed some refinement.

Several manufacturers expressed displeasure that a particular model did provide nearly as much sound reduction, looking at an average of ten shots, as a similar model of a competitor. Yet that louder model might be an integrally suppressed .22 pistol that delivers more velocity, which is important for anyone shooting a live target instead of punching paper or pop cans. Another suppressor might be louder than a competing model, but it’s half the price of the ultraquiet competitor, or significantly shorter or lighter or more durable. The sound moderator from one manufacturer comes to mind as an example; it is small, light and durable while providing significantly less sound reduction than the manufacturer’s own and competing full-sized suppressors. But the compact size is especially valuable when fitted to an entry weapon, and the moderator will enhance command and control while protecting the operator from short-term and long-term hearing loss. A silencer or moderator that is relatively loud may still be an appropriate tool for a given set of circumstances.

There are more subjective considerations as well. For example, a somewhat louder suppressor or integrally suppressed firearm with superb craftsmanship and cosmetics might make a more handsome and appropriate family heirloom. Sometimes maximum sound suppression is, indeed, the single most important design or performance criterion when selecting a suppressor for a particular application, but sometimes it’s well down on the list of priorities. Here’s a list of design and performance criteria that should be used when evaluating suppressors. How these criteria are ranked in terms of priority will vary with each and every end-user’s circumstances and requirements.

Criteria for Suppressor Selection

1. length
2. diameter
3. weight
4. materials
5. durability of construction (operational lifespan)
6. tonality of sound signature (dominant frequency or pitch)
7. sound pressure level of sound signature (or net sound reduction)
8. first-round pop
9. wet or dry technology?
10. effect on projectile velocity
11. effect on accuracy
12. handiness (human engineering)
13. cost
14. appearance
15. maintenance requirements
16. mounting system
17. type of finish
18. reputation of manufacturer
19. time to drain if full of water (relevant for some SpecOps requirements)
20. time to mount and dismount from weapon (relevant for some SpecOps requirements)
21. quality control
22. ability to deliver required quantities within any time constraints

The learning process at the suppressor trials was by no means limited to the sound testing and discussions on design and performance criteria. Throughout the very long day, the various manufacturers chatted with each other, discussing the fine points of suppressor design, such as how a designer was trying to manipulate gas flow with a new baffle design, problems trying to reduce first-round pop, or the use of exotic materials and fabrication techniques. Suppressor designers frequently offered suggestions to a competitor on how to solve a particular problem. That is not to say that folks swapped their most valuable proprietary knowledge, but they shared information of a depth and quality that I found both remarkable and heartwarming. I know of no other small, highly competitive industry where the principals are so gracious and genuinely helpful to their competitors. Mark White of Sound Technology added to this sense of community by throwing a barbecue for all of the participants at the end of the day.

While space constraints preclude reporting the data here, it is appropriate to highlight a sampling of products that impressed me. Ralph Seifert of R.A.S.E., for example, has developed an innovative baffle design for the .22 rimfire that provided impressive performance in his Labyrinth (an integrally suppressed Ruger 10/22 rifle) and Photon (an integrally suppressed Mountain Eagle pistol). The Photon is remarkably light since it uses a largely plastic pistol plus an innovative carbon fiber suppressor tube. The Photon also features a reinforced barrel which may well eliminate the durability problems often associated with earlier attempts to suppress this pistol by other manufacturers.

Don Austin Wagenknecht brought a particularly diverse product line, ranging from a suppressed cane gun, to an efficient suppressor for the Cobray M11/9 submachine gun, to an ingenious muzzle can for the S&W Model 422 pistol.

While John’s Guns suppressed Marlin Camp Carbines provided good performance in a handy package, the integrally suppressed Ruger 22/45 pistol and Ruger 10/22 rifle designed by John Tibbetts were particular crowd pleasers. His suppressed Ruger Mark II was the quietest integrally suppressed Ruger pistol of the day, beating such industry benchmarks as the outstanding Operator from Gemtech and revolutionary Amphibian from AWC Systems Technology. His Ruger 10/22 was also one of the quietest of the intergrally suppressed 10/22s evaluated during the trials.

Mark White introduced one of the most popular designs of the day—as evidenced by the crowd of dealers wanting to test fire the system during the picnic following the trials—with his Dark Star suppressor mounted on a Ruger Model 96 lever-action rifle firing 260 and 325 grain subsonic .44 Special loads. Originally developed for 7.62x51mm sniper rifles, this superb suppressor made the .44 rifle quieter than a factory original H&K MP5 SD while delivering far superior terminal ballistics. The crowd waiting to fire the suppressed .44 only dispersed when White finally ran out of ammunition.

Jonathan Arthur Ciener, who is the oklest continuously operating suppressor manufacturer in the United States (and one of the oldest in the entire world), had such a confidence in his earliest work that he brought original prototypes from the 1970’s for testing. Even though these designs are several decadesold , I was most impressed by their durability, outstanding workmanship, and the fact that they still provided solid sound reduction compared to the very latest generations of suppressors brought by other. Perhaps the best way to put Ciener’s work in perspective is to note that he was the first to design an effective suppressor for the UZI submachine gun. The salient point is that Ciener developed that UZI suppressor soon after a team of scientist working for Uncle Sam had concluded that it was theoretically impossible to design an effective and practical suppressor for the Uzi, after the goverment had thrown cubic dollars and numerous engineers at the project. It is safe to say that Jonathan Arthur Ciener has played a piotal role in the development of silencer technology as well as in the popularization of that technology with American civilians. The entire industry owes him a considerable debt of gratitude for his contributions.

SIOPTS provided a titanium suppressor with quick-mount system that fastens directly to an unmodified M16A2 or M4 flash hider, something that no one else has accomplished to my knowledge. Furthermore, SIOPTS developed a very heavy, frangible tungsten subsonic round that actually cycles the action—another “impossible dream” that has become reality. While the round provided disappointing accuracy during the trials, it turned out that a loose flash hider on the rifle was the culprit. Subsequent testing demonstrated that the round is capable of delivering a head shot at 100 yards, as long as a barrel with a 1 in 7 rate of twist is used.

Joe Gaddini of SWR was the only manufacturer to bring suppressors for the .40 S&W variant of the MP5 submachine gun, offering a compact sound moderator, a medium-sized suppressor, and a full-sized suppressor. A former engineer at Knight’s Armament Company, Gaddini takes great pains not to infringe upon the proprietary designs of KAC, which is something I greatly admire. His design strategy is to minimize first-round pop at the expense of the average sound pressure level, based on the premise that—for serious applications—the sound signature of the first shot is most critical. While his .45 caliber suppressor for the H&K Mark 23 pistol is louder than the KAC SOCOM suppressor, for example, the amount of first-round pop is less.

That said, the performance of the SOCOM suppressor designed by Doug Olson and Reed Knight was most impressive, producing a sound signature that was less than many suppressed .22 rimfire rifles and pistols. As impressive as the sound signature was, I was even more impressed by the suppressor’s overall design in terms of baffle configuration, fabrication, metallurgy, durability, and finish. Just the tooling to manufacture the complex fluted baffles cost several hundred thousand dollars, and a robot performed all of the complex welding to provide excellent quality control. The Nielsen device in the rear of the suppressor that enables the pistol to cycle reliably—together with the ability to easily zero the point of impact when mounting the suppressor on any pistol—represent remarkably sophisticated engineering. While the Mark 23 pistol with Knight suppressor is a large and heavy package on paper, the reality of handling this system is quite different than mere statistics suggest. Balance and handling are superb, making it easy to deliver rapid double taps at 50 yards. The pistol’s sound signature is significantly quieter than an MP5 SD integrally silenced submachine gun, and it delivers vastly superior terminal ballistics. The H&K Mark 23 pistol and Knight suppressor together form a new and impressive state of the art.

Gemtech fielded a new 9mm pistol suppressor called the Vortex-9, which provided a remarkable 28 dB reduction when fired dry on a Beretta 92F pistol and 35 dB after a half teaspoon of water was poured into the back of the suppressor and allowed to seep through ported baffles into structures that trap the water so it doesn’t leak from a holstered suppressor. The Vortex-9 did not smoke or spatter the operator with droplets of greasy grime, and the impressive performance when wet seems to last for two magazines-worth of shooting. While Gemtech’s M4-96D quick-mount suppressor for the M4 carbine normally equals or slightly outperforms the KAC M4-QD with M855 ball ammo, the Knight suppressor dramatically outperformed the Gemtech suppressor with Winchester USA (so-called White Box) 55 grain fodder. While most suppressors perform very well with Winchester USA pistol ammunition, we learned during the course of the trials that many suppressors do not perform as well as expected when employed with Winchester USA ammo of rifle caliber. Winchester has just discontinued the production of rifle caliber paramilitary ammunition, so this phenomenon can be relegated to a point of historic interest.

John Weaver of JRW fielded a diverse array of suppressors, from an impressive integrally suppressed Ruger 10/22 rifle to a suppressed Sako rifle in .300 Whisper that was quieter than an H&K MP5 SD. JRW’s OTB 22 muzzle can provided excellent performance shot dry on a Marlin 39A rifle and wet on a Walther PP pistol.

The integrally suppressed firearms made by Curtis Higgins of S&H Arms of Oklahoma provide an almost ideal maximum projectile velocity without sacrificing sound reduction. In fact, the

S&H suppressed 10/22 rifle was significantly quieter than most silenced 10/22s I’ve tested. The impressive R.A.S.E. 10/22 beat the performance of the S&H gun by 1 decibel but delivered 43 fps less velocity. I’ve tested some 10/22s that delivered nearly 200 fps less velocity without being nearly as quiet as the S&H gun. It is interesting, however, that one of my favorite .22 pistols of the day was also one of the loudest of its type. Higgins developed an exquisitely handsome suppressed High Standard pistol that is 12 decibels louder than his standard suppressed Ruger Mark II pistol, and the silenced High Standard also has a substantial first-round pop. But it uses a suppressor tube that has a diameter of just 7/8 inch, which enables Higgins to make a package of extraordinary aesthetic appeal. Finally, I can’t go on without mentioning the S&H clone of the H&K MP5 SD, which delivered substantially better sound reduction and substantially higher projectile velocity with both supersonic and subsonic ammunition than a factory original MP5 SD. That’s a most impressive engineering achievement.

Dale Summers of Summers Machine Enterprises produces integrally suppressed Ruger rifles and pistols that give a good mix of sound reduction and projectile velocity, while delivering much better than average accuracy. Summers has a small but fiercely loyal following of regular customers, one of whom provided the pistol for testing. The Spec Op’s Shop provided an interesting array of titanium suppressors for the Ruger 22/45 pistol, Beretta 92F pistol, MP5 submachine gun, Remington PSS rifle, and Colt M4 carbine. The Spec Op’s Shop 9 inch variant of the 5.56mm Viper outperformed the very successful HRT from AWC Systems Technology.

Finally, we tested the subsonic 5.56x45mm White Tip ammunition developed by Whit Engel of Engel Ballistic Research. Using an aftermarket M4 clone and a Gemtech M4-96D suppressor, we tested two variants of subsonic ammunition: one features a 55 grain projectile, while the other uses a 69 grain projectile. The suppressed sound signatures were 117 and 118 decibels, respectively, which is quieter than many suppressed .22 rimfire rifles and pistols. Using a barrel with a twist of 1 in 9, these subsonic rounds provide the capability to deliver head shots at 80 yards.

My thanks to all of the suppressor manufacturers and volunteers who made the 1997 Silencer Trials a success. Forthcoming issues of Small Arms Review will provide a more detailed examination of sound suppressor technology from each of the participants in the 1997 Silencer Trials. We hope to make this an annual event which will draw participants from throughout the United States and overseas as well. The trials provided a great learning experience for all of the manufacturers, volunteers, and dealers who participated in the event.

Participating Manufacturers

Don Austin Wagenknecht
12400 Blue Ridge Blvd.
Grandview, MO 64030

Engel Ballistic Research
Rt. 2, Box 177C
Smithville, TX 78957

Gemtech
P.O. Box 3538
Boise, ID 83703

John’s Guns
3010A Hwy. 155 N.
Palestine, TX 75801

Jonathan Arthur Ciener, Inc.
8700 Commerce Street
Cape Canaveral, FL 32920

JRW
3425 Yule Tree
Edgewater, FL 32141

Knight’s Armament Co.
7750 9th Street SW
Vero Beach, FL 32968

R.A.S.E.
P.O. Box 866
Cocoa, FL 32926

S&H Arms of Oklahoma
P.O. Box 121
Owasso, OK 74055

SIOPTS
570 A Industrial Park Dr.
Newport News, VA 23608

Sound Technology
P.O. Box 391
Pelham, AL 35124

Special Op’s Shop
P.O. Box 978
Madisonville, TN 37354

Summers Machine Enterprises
Route 7, Box 672
Thomasville, NC 27360

SWR
119 Davis Rd., Suite G-1
Martinez, GA 30907