Firearms and ammunition

by Frank Iannamico
From: http://www.smallarmsreview.com/january.htm

The revolutionary MP38 machinepistole made its combat debut with the German blitzkrieg invasion of Poland that began on 1 September, 1939. Other than some self-inflicted casualties on the German troops from the MP38’s marginal safety system, the weapon was a huge success.

The Germans began using the submachine gun, or maschinenpistole, near the end of WWI when they developed and adopted the full automatic 9mm MP18.I. They felt the submachine gun would have great value in the close quarter combat situations encountered when the trenches were overrun. While the defenders of the trenches would be attempting to protect themselves with their limited capacity bolt action rifles and bayonets the Germans would be spraying them with submachine gun fire at 500 rounds per minute! The German MP18.I was the first weapon to use the soon to be common open bolt system. It was also the first of many German submachine gun designs.

World War One ended with the German surrender in November 1918. The Allies drew up an agreement called the Treaty of Versailles; the treaty was extremely harsh and restrictive. The Germans had little choice but to sign it. The treaty would cause much unrest among the German people and plant the seeds for WWII.

The Treaty of Versailles prohibited the Germans from developing or testing any type of military weapons. All existing WWI weapons were ordered destroyed by the Inter Allied Control Commission. Although the Germans were allowed a 100,000 man self defense force, the Reichswehr, they were restricted to the type of weapons they could issue. Submachine guns were prohibited, except for limited use by the German police departments. The police issued the MP18.I.

Despite the harsh restrictions, the Germans secretly continued to develop and test many new weapon designs for the war they knew was coming. Rather than manufacture and stockpile existing designs, they wanted to continually develop new weapons so when war did come, they would be equipped with the most advanced weapons available. While most of the Allies of WWI were enjoying peace, the Germans were secretly preparing for war.

Most of the submachine guns the Germans developed between the wars were all very similar to the MP18.I model. They all looked like short barreled carbines. Except for a few minor variances they all functioned pretty much the same. The MP38 was the first German production weapon that was different.

In January 1938 the German Heereswaffenamt (Army Weapons Office) requested a lightweight, compact, rapid firing 9mm weapon for paratroopers and armored crews. The development time to the resulting MP38 in August of that same year was extraordinarily brief. The reason for the seemingly rapid development of the weapon was due in part to the model Erma Werk already had under development. One prototype was the MP36. The MP36 was virtually unknown for many years, due to extreme rarity of surviving examples.

The Only markings on the MP36 are located under the weapons foregrip. They read “EMP36″ Erma Erfurt. Note serratted butt stock and disassembly knob.

Although the MP36 is similar to the MP38 there are some notable differences. The MP36 is selectfire, it has a fire mode selector located above the trigger housing. The fire selector is remarkably similar to that on the Haenel MP41 model. All of the MP36’s components are manufactured from machined steel stock.

The MP36 has wood furniture instead of plastic as used on the MP38/40. The pistol grip panels are also finely checkered wood. The folding metal stock of the MP36 is very similar to that of the later production design, except there are no springs, detents or release buttons. The stock folds and extends under the friction of the snug fitting parts. The butt plate has machined grooves instead of being smooth.

The front sling swivel can be easily rotated to either side. The magazine catch is the latch type similar to those used in earlier designs, rather then the button release of the MP38/40 design. The magazine release lever is located at the rear of the housing.

The bolt assembly is similar to the MP38/40 except that the front portion of MP36 bolt is a separate piece, and is attached by a locking screw. The front sight is a driftable unprotected design. The rear sight is similar to the MP38/40. The MP36 is devoid of any identification markings except for the underside of the wooden foregrip. This area is marked “ERMA ERFURT” “EMP 36″, the EMP designation is for Erma Machine Pistol.

The MP36 cocking handle like the MP38/40 is located on the receiver’s left side. This was the very first German weapon to feature this. The idea behind the left side cocking handle was that it allowed the shooters hand to remain on the pistol grip (and finger near the trigger), allowing him to easily cock the weapon with his weak hand. It was thought that this would make for a more rapid magazine change, saving seconds and perhaps the shooter’s life. The knob is similar to that on the earlier Erma EMP weapons. The magazine housing is unique in that it is slightly canted approximately 30 degrees to the left. The magazine is different, and not interchangeable with that of the MP8/40. When this weapon was captured there was no magazine in it. An MP40 magazine was adapted to fit. No original MP36 magazine has ever been located or documented. The MP36 field stripping procedures are very similar to those of the MP38/40.

Great room in Karinhall where the MP36 s/n 014 was believed to be kept by Gцring.

This particular MP36 is serial number 014, and is a very well made piece. The finish is a very fine, highly polished commercial blue. The wood is made of fine sculptured walnut. Virtually every part is stamped with the weapon’s serial number, even the heads of the screws. The weapon is obviously a presentation piece, the type often presented to high ranking officials by the weapons manufacturers.

This particular MP36 has a very colorful story of how it was obtained during WWII. In 1943 a group of volunteers was organized to go on a top secret covert mission. The mission’s objective was to assassinate Hitler’s Reichmarshall and head of the Luftwaffe, Hermann Gцring. The attempt on Gцrings life was planned to take place at Karinhall located some 40 miles northeast of Berlin. Allied intelligence sources had reported that Gцring would be present at Karinhall and that the grounds would be lightly guarded. Karinhall was one of Gцring’s many extravagant residences. It was named after his late wife who had died prematurely in 1931.

The Allied team quietly parachuted into the area at night virtually undetected. Once they reached the grounds surrounding Karinhall they soon discovered that the mansion was being guarded by a private army of Gцrings elite Fallschirmjдger troops, all well trained and heavily armed. After the German troops discovered the team, a fierce firefight was soon underway.

Right side view of the canted magazine housing and release lever.

During the confusion a particular U.S major managed to slip into the main building to search for Gцring. While he was looking around the main hall he spotted a strange, unfamiliar weapon hanging on the wall. Thinking it may be of interest to U.S. intelligence, he removed it and placed it in his pack. He then decided that the mission was failing, and decided to try fighting his way out of a rapidly deteriorating situation. He and a very small portion of the original Allied team managed to escape and make their way back to safety.

The weapon remained in the major’s possession for the remainder of the war. In 1945 when he returned to the United States he brought the MP36 home as a war souvenir. He stored the gun away and went on with his post war life. The major was unaware of just what a rare piece he had in his possession.

Eventually the weapon was sold and changed hands a few times in subsequent years. Today this unique weapon is in the fine collection of German weapons collector Lou Pacilla. It is the only transferable MP36 in the world. There is only one other example of the MP36 known to exist. That MP36 is serial number 001, and is in the possession of a military museum in Prague, Czechoslovakia. Reportedly the condition of that weapon is also excellent.

Hitler eventually ordered the Fallschirmjдger troops that were assigned to defend Gцring’s Karinhall into the line defending Berlin from the invading Russian troops in 1945. The Russians took prisoner the troops who weren’t killed.

Gцring ordered his engineers to destroy Karinhall as the Russians were sighted approaching the Schorfheide forest surrounding the estate in 1945. Although it was his favorite mansion, he did not want it to fall into Russian hands intact.

Right side view of the trigger area. Fire selector button is shown just above trigger.

The Allied forces eventually captured Hermann Gцring, and he was placed on trial along with the other remaining Nazi leaders at Nuremberg. He was convicted of various war crimes and sentenced to death by hanging. His request for an “honorable” death before a military firing squad was denied. Gцring committed suicide by swallowing a cyanide capsule before his sentence could be carried out.

The US Army Major who participated in the raid on Karinhall passed away recently after retiring from a very successful career in law enforcement.

The Erma MP36 serial number 014 has survived the past 50 plus odd years in the same immaculate condition as the day it was liberated from Hermann Gцring’s mansion. The official version of the mission is still classified.

France’s Unmusical Bugle
by Peter G. Kokalis

French soldiers refer to it as “le Clairon.” But this bugle spits bullets. It is not a pretty weapon - in fact, it’s downright ugly. Esthetics, however, are of small consequence in the design of efficient weaponry.

France’s newest service rifle, the FA MAS (Fusil Automatique, Manufacture d’Armes de St. Etienne), has already demonstrated itself to be an effective and generally well-conceived piece of ordnance. First introduced in 1973 and subsequently modified, the FA MAS was adopted by the French armed forces and placed into production in 1979. Manufactured by GIAT (Groupement Industriel des Armements Terrestres) at their St. Etienne arsenal, a semiautomatic-only version of this interesting assault rifle has been imported in limited quantity by Century International Arms.

After generations of discordant calibers - such as the 7.5mm rifle and 7.65mm Long pistol cartridges - the French finally decided to play in NATO’s orchestra and chambered the FA MAS for what is essentially the U.S. 5.56×45mm M193 cartridge. It differs only by virtue of its Berdan primed steel case. Compatibility with NATO has been served and France now has a cartridge with proven efficiency in causing casualties.

Hands-on use of this weapon has produced compliments - SOF’s Paul Fanshaw, who employed the FA MAS rifle extensively while serving as a platoon sergeant in the French Foreign Legion, awards it a clean bill of health in all regards.

Of so-called bullpup configuration, the FA MAS measures only 30.28 inches in overall length. Complete with flash suppressor, the barrel is 19.5 inches long. Oddly cut with only three grooves, the rifling’s rate of right-hand twist remains one turn in every 12 inches. An optional pitch of one turn in 9 inches is available as a compromise to accommodate the SS109 projectile. But in spite of its compactness, the FA MAS weighs 8.0 lbs. empty and minus the bipod - at the outer limits by today’s standards. Steel parts are phosphate finished and the receiver has been anodized gray.

Firing from the closed-bolt position, the method of operation is by means of delayed blowback. While this principle smacks of Heckler & Koch (early prototypes of the FA MAS were pictured with the G3 bayonet), the delay system has been taken directly from the French AA 52 General Purpose Machine Gun.

A black plastic lower handguard, pinned to the barrel and receiver, extends back to the magazine well and cannot be removed. To accommodate the bullpup configuration, the trigger mechanism and pistol grip have been mounted to the lower handguard, forward of the magazine well. The ergonomically-designed pistol grip has three finger grooves and a storage trap which contains a plastic bottle of lubricant.

The sheet-metal trigger guard can be pulled away from its rear retaining pin and rotated 180 degrees for firing with gloves under arctic conditions. The trigger is connected to a long, thin strip of sheet-metal which rides in a slot on the right side of the receiver and reaches the hammer mechanism located at the rear of the receiver. Trigger pull-weight was a spongy and variable 8 to 9 lbs. on our test rifle. On the semiauto-only FA MAS, pressing the trigger draws this spring-loaded bar forward to pull both the primary and secondary sears away from the hammer’s notch.

A spring-loaded, plastic catch in front of the magazine well must be pressed back to remove a magazine. Magazines are inserted by pushing them straight into the well. No rocking motion is required. There is no hold-open device. But who cares? Thirty million Kalashnikovs have been manufactured without one, as well as millions of G3s and Galils. And they all seem to do just fine in combat.

FA MAS magazines hold 25 rounds and, in my opinion, are superior to those of the M16 series. While not as heavy as Galil or Beretta Model 70 magazines, the sturdy steel bodies are straight-line, without any curvature, with substantial locking tabs punch-welded to the exterior, front and rear, Two-piece floorplates insure rapid disassembly. Only the follower is plastic.

Because the firing pin is withdrawn from the bolt face by the delay lever’s rotating cross-piece, there is no need for a spring. Other components of the bolt group include a removable bolt head with a spring-loaded, centrally located “bump”-type ejector, and an extractor and dummy extractor plug.

Being a bullpup, the FA MAS can be modified to fire from either shoulder. To change the FA MAS from right- to left-hand ejection, withdraw the bolt head after removing its notched retaining pin on top of the bolt body, insert the extractor into the left side of the bolt head and the dummy plug into the right side. The extractor will now spin empty cases out to the left. Nothing else is required for left-hand ejection, other than to snap the cheekpiece onto the right side of the buttstock.

This checkpiece was neoprene-covered sheet-metal on early specimens. It is now a light plastic molding, but still quite comfortable. Both ejection ports are cut into the plastic buttstock molding - one or the other being blocked by the cheekpiece. A spring buffer in the top of the buttstock compresses about an inch before rebounding. To reduce costs, it has been eliminated on the semiauto-only version as its cushioning effect on the reciprocating parts is not required in semiautomatic fire. There is a stippled, neoprene buttplate with fixed sling swivels on either side.

The upper handguard certainly contributes more than its share to this rifle’s grotesque appearance. It also acts as a carrying handle and protects the sights which rise 3 inches above the bore’s axis. A lightweight tubular aluminum bipod has been bolted to a bracket under the handguard. The non-adjustable legs, with plastic feet, fold along the sides of the handguard when not in use. To employ, simply pull out on the leg and rotate to the extended position. This useful feature adds only 6 oz. to the overall weight.

Each FA MAS is equipped with a cleverly designed, ambidextrous web sling. The rear portion attaches, in the conventional manner, to either of the sling swivels on the buttstock. The front clips mount on either of the bipod legs’ axis pins, which permit rotation of about 220 degrees and a wide variety of carrying positions.

A spare parts and cleaning kit is also included and it consists of an ejector and spring, extractor, dummy extractor plug, bolt-head retaining pin, plastic cleaning rod with brass tip, bore and chamber brushes, camel’s hair brush and a really useful prismatic bore scope.

While bayonets have certainly become an anachronism on today’s battlefield, armies continue to issue them. Little time was wasted on designing a bayonet for the FA MAS. What is essentially the MAS 49/56 (French army rifle which preceded the FA MAS) bayonet was adopted. Blade shape resembles that of the U.S. M4-M7 series of knife bayonets. Grip panels are black, uncheckered plastic. There are two muzzle rings. One fits over the flash suppressor, the other on the barrel collar. The rear muzzle ring diminishes the bayonet’s value as a fighting or utility knife. The black plastic, locking scabbard has been riveted to a web frog in the U.S. manner.

Firing the FA MAS, or any bullpup assault rifle for that matter, can be somewhat unsettling the first time around. With your face directly over the action, fleeting thoughts of what might happen if the weapon self-destructs are bound to occur. They are but fantasies of course, and nothing we stuffed into the FA MAS brought us anywhere close to red-lining its engine.

Most of the firing sequences were conducted with Portuguese M193-type ball ammunition of 1982 manufacture (headstamped ‘FNM 82-17′). What a pleasure it is to fire an assault rifle in this caliber and not have to contend with bolt-over-base stoppages such as those induced by an M16 magazine. There were no malfunctions of any kind.

Accuracy potential was more than acceptable. With winds gusting at 25 mph, 3 MOA, with horizontal dispersion only, was the best we could do at 100 yards.

Felt recoil was quite low, but the perceived muzzle blast, because of the bullpup configuration, was loud. Ejection patterns, which are either to the right or left in direction, varied from 10 to 20 feet from the rifle with a high trajectory for the empty cases. Some cases spun back to scuff the stock slightly.

While they have no heat shields, the handguards are far enough from the barrel to permit a substantial volume of air to circulate. Neither handguard overheated at any time during the test. Balance and handling charactefistics are excellent and the rifle can be shifted quickly to engage multiple targets.

The more I shoot it, the more this grotesque hunchback grows on me. Its unsightly geometry becomes quickly muted by its superb performance. Regardless of the U.S. military’s antipathy toward them, bullpup designs will continue to proliferate as the quest for ever more compact individual weapons marches forward. Fit for anyone’s front line, the FA MAS should give both the Austrian Steyr AUG and the British Enfield SA 80 a stiff run for the money.

Military organizations and law enforcement agencies can obtain versions with scopes integrated into the carrying handles, training rifles firing 4.5mm pellets by means of C0&sub2; and short-barreled models with 16.5-inch barrels. A new carrying handle that will accept any NATO STANAG scope is also under development.

From: www.remtek.com

Taking a rifle out into the woods is a pleasure that’s just not enjoyed enough anymore.

Perhaps that’s because a handy, comfortable-to-carry, woods rifle hasn’t been available for decades. Action Arms’ new Timber Wolf has changed all that. Here again is a well-balanced, offhand rifle that rides at one’s side, almost weightlessly, throughout a leisurely walk under a forest canopy.

The classic woods rifle - revisited

The new Timber Wolf brings together a combination of the style and features of slide-action rifles of an earlier era: A time when quality and workmanship were hallmarks of firearms manufacturing. It was also a time when life’s pace allowed sportsmen a relaxed afternoon of “woods loafing.”

The new Timber Wolf makes a great companion for your favorite revolver

Chambered in the popular .357 Magnum cartridge, this slide-action carbine is light weight, and it takes down to be even easier to pack along. Its carbine-length barrel squeezes every bit of performance out of any magnum load, and it’s just over 18 inches long.

Classic looks don’t compromise modern technology and features

The Timber Wolf’s slim lines and walnut stock are reminiscent of a bygone era, but features like integral scope bases and a sear-locking safety assure that this is a rifle for today. Naturally, open iron sights are included. The milled receiver and barrel meet the same rigid specifications Israel Military Industries builds into all of their firearms, including the legendary UZI.

Your next rifle ought to be one you’ll shoot a lot.

The Timber Wolf is fun to shoot. It shoots .38 Special or .357 Magnum, and it is as much at home on an indoor range as it is in the woods. It takes down and is easy to carry. Weighing only around five and a half pounds, the Timber Wolf has all of the features that make a rifle classic. Ask to see one, feel its balance and find out for yourself.

Information courtesy of Action Arms, Ltd., circa 1989.

From: remtek.com

The world’s most famous military handgun has been improved. In the early twenties, John Moses Browning and FN Herstal jointly designed the original Browning 9mm Hi Power single action pistol. Today, FN’s HP pistol is in service in more than 100 countries around the world, and it has a well-established reputation for high quality and total reliability. FN’s newer, product-improved MK3 represents decades of user feedback and offers a subtle balance between tradition and evolving technologies.

Improvements over the HP pistol include:

Ergonomic grips that significantly improve handling and contribute to the shooter’s comfort.

New sights for improved accuracy. These are precision machined and notched for optimum contrast. Both front and rear sights are dovetailed to ease zeroing and to allow for the installation of tritium night sights.

Ambidextrous safety for added security during left-handed operation.

The MK3 retains the Hi Power’s original mechanism as well as all of the major parts and vital advantages of its venerable predecessor. This precludes any deviation whatsoever from the Hi Power’s long-standing reputation for safety and reliability under even the most adverse conditions. The MK3’s sturdy and simple mechanism also ensures long component life and simple maintenance.

To simplify the transition from Hi Power to MK3 and to take advantage of an existing and highly-effective design, the MK3 also retains the Hi Power’s numerous and proven safety mechanisms. These include:

a mechanical safety lever, now ambidextrous, that allows the weapon to be carried fully safe,

a visable hammer which indicates whether or not the weapon is cocked,

a half-cocked notch that catches the hammer if it slips during cocking or de-cocking,

a firing pin spring design which prevents inadvertent discharge if the weapon is dropped with a round chambered and

a magazine safety that disengages the trigger when the magazine is removed.

MK3 Technical Specifications

Caliber: 9×19mm NATO
Operating principle: Short recoil Browning mechanism
Trigger mechanism: Single action only
Magazine capacity: 13 rounds
Overall length: 200mm (7.9 in)
Barrel length: 118mm (4.6 in)
Sight radius: 159mm (6.2 in)
Weight, unloaded: 930g (2 lbs)
Weight, loaded: 1,085g (2.3 lbs)
Finish: Black, corrosion-resistant semi-gloss

From: http://www.remtek.com

by Al Paulson

The P90 Personal Defense Weapon was originally designed by Fabrique National Herstal SA of Belgium as a personal defense weapon for troops whose primary mission is something other than the use of small arms. Thus, the P90 is intended for people such as vehicle drivers, operators of crew-served weapons, support personnel and other troops who are often issued sidearms or submachine guns. The goal was a select-fire weapon of ultra-compact design that would provide superior hit probability to the aforementioned weapons out to greater distances thanks to the new compact 5.7×28mm round. These characteristics, combined with the availability of SB193 subsonic, L191 tracer and SS190 supersonic ammunition for the P90, provide a very interesting package for Special Operations as well as for law-enforcement, counter-terrorist, security and executive-protection applications.

Many of these additional missions would depend upon - or be enhanced by - the availability of a compact sound suppressor. That suppressor would have to be capable of sustaining substantial full-auto fire with standard duty ammunition (an impossible dream until very recently), while providing enough suppression with subsonic rounds to hide the fact that a shot has been fired when the tactical situation demanded stealth. FN Herstal SA asked Gemtech to develop a military quality suppressor for the P90 that would be compact, tolerate full-auto fire, and incorporate a snap-on quick mount which would retain the FN muzzle brake or at least incorporate that design into a replacement fixture.

Gemtech’s design team of Dr. Phil Dater, Greg Latka, and Jim Ryan devoted a great deal of time and energy into the project over the course of a year. Their impressive M4-96D suppressor for the M4A1 carbine - which Gemtech initially developed for the Naval Surface Warfare Center - was already in production, and this became the inspiration for the new SP90 suppressor. The process of adapting the M4-96D technology was more complex than one might guess. Some qualities of the new system made the design process easier, while others would provide challenges.

A plus for the designers was that the Five-seveN (5.7×28mm) cartridge produces a substantially smaller volume of combustion gases than the 5.56×45mm round. Less gas means that the suppressor has less work to do, so the Gemtech team was able to make the SP90 shorter, smaller in diameter and substantially lighter than previous designs.

Most of Gemtech’s design effort focused on engineering a revolutionary baffle stack that would not increase the P90’s cyclic rate beyond acceptable limits. This challenge, which one would expect from any compact blowback weapon, appears because a suppressor increases back pressure, which increases the cyclic rate of the weapon. At least theoretically, a suppressor could increase the back pressure of any compact blowback weapon to the point that the magazine spring does not have enough time to present the next round for the bolt as it cycles forward. Thus a design goal for any compact weapon is to tune the design of a suppressor so that bolt speed (i.e., cyclic rate) of the suppressed weapon falls within the optimum range for both the weapon itself and its magazine. Thus the contradictory challenges are to minimize back pressure for optimum reliability while creating maxirnum turbulence inside the suppressor to optimize the amount of sound reduction. In order to meet these challenges, Gemtech developed a baffle stack in which no two baffles are the same design.

Another design challenge was to develop a robust and foolproof quick mount for the SP90 suppressor. Since it proved impractical to design a suppressor mount that would directly latch onto the outstanding FN muzzle brake, the Gemtech team decided to marry their Bi-Lock snap-on quick mount with the FN muzzle brake.

SP90 Design

Gemtech’s remarkable spring-loaded Bi-Lock mounting system provides excellent alignment with the P90 barrel and a robust means of attaching the SP90 suppressor that never loosens during firing (unlike screw-on suppressors using a single-point mounting system, which tend to loosen when subjected to semiautomatic or full-auto firing, unless permanently attached with ROCKSETT sealant or silver solder).

The name of this patented Bi-Lock mounting system comes from the two alignment lugs on the muzzle brake, which engage a spring-loaded collet in the back of the suppressor. The moving parts are sealed to minimize fouling from carbon and powder residue. To install the Gemtech SP90 suppressor on a barrel fitted with a Bi-Lock muzzle brake, simply align the suppressor with the brake, push down and rotate the can 90 degrees clockwise (as seen from the front) until the device can no longer be rotated, and allow the spring pressure to lock the suppressor firmly against the Bi-Lock’s twin lugs. Each lug has a different size, so there is only one way to install thesuppressor. This feature minimizes the shift in the point of impact whenever the suppressor is mounted and keeps the shift repeatable (i.e., predictable).

Since stops in the mount prevent rotating the suppressor past the locking recesses in the interface piston that mate with the compensator lugs, the mounting procedure is both positive and very fast. Furthermore, the amount of pressure generated by the intemal spring during mounting is considerably less than some quick mounts I’ve used on other weapons, making the installation process easier and faster, without sacrificing security.

When removing the suppressor soon after firing, be aware that the silencer could be dangerously hot. Use a heavy glove, hat or other protection to avoid burns. To dismount the Gemtech SP90, push it backward about 0.1 inch (3 mm) until the suppressor can be rotated counterclockwise (as seen from the front). Rotate the can 90 degrees and pull the suppressor clear of the flash hider. The Bi-Lock mount permits installing or removing a sound suppressor in just 1.5-3 seconds. It is safe to say that the Bi-Lock mount is an impressive engineering achievement.

The Gemtech SP90 suppressor is constructed from 304 stainless steel tubing, 303 stainless steel barstock, hardened 440C stainless steel for the interface piston, and Inconel for the blast baffle at the rear of the baffle stack. Inconel is particularly resistant to the heat and erosive effects of hot combustion gases, especially when the suppressor is subjected to fullauto fire. The Bi-Lock compensator is machined from 4140 steel which is then hardened. The SP90 is 7.25 inches (18.4 cm) long and 1.37 inches (3.5 cm) in diameter, and the suppressor weighs 19.4 ounces (550 grams). All suppressor components are coated in a matte black oxide, and the interface piston receives an additional coating of Sandstrom Products 9A Dry Film Lubricant to enhance corrosion resistance,

From a subjective point of view, the relatively modest length and weight of the SP90 gives the suppressor excellent handling characteristics when mounted on the FN P90. Whether engaging targets at arm’s length or at 100 yards (91 meters), target acquisition was very rapid and hit probability was outstanding. The sound signatures produced by the suppressed P90 were quite impressive. When using the supersonic SS190 ammunition, the surprisingly mild cough of the suppressor was followed by bullet flight noise, which was a muted and rather eerie ripping sound that ended with the distinctive thud of bullet impact. When using subsonic SB193 subsonic ammunition, the muzzle signature seemed dramatically quieter than an H&K MP5 SD, bullet flight noise was a barely perceptible hiss, and the noise of bullet impact was easily the dominant sound. While this is a very interesting design that produces a satisfying sound signature when fired with either supersonic or subsonic fodder, there is no substitute for rigorously evaluating the performance of a suppressor with repeatable and standardized scientific methodology. To this end, I tested the performance of the Gemtech SP90 suppressor using the following procedures.

Performance

Conclusions

The P90 is compact, handy in close quarters, and yet provides rapid target acquisition and outstanding hit probability out to 150 meters. When fitted with the Gemtech P90 suppressor and using supersonic ammunition, the weapon is significantly quieter than a suppressed M4A1 carbine. This has direct implications regarding command and control in confined spaces, as well as both short-term and long-term hearing loss experienced by personnel operating in limited spaces. When using subsonic ammunition, the suppressed P90 is dramatically quieter than an H&K MP5SD and is even quieter than some integrally suppressed .22 rimfire rifles, making a very stealthy weapon. The Gemtech suppressor will tolerate an unprecedented amount of full-auto fire for an intermediate cartridge, mounts or dismounts in the time required for a magazine change, and will not loosen during prolonged firing.

Assuming the terminal ballistics are suitable, the FN P90 with Gemtech suppressor seems even better suited for law-enforcement applications than for its originally intended role as a military personal defense weapon. Whether used as an entry weapon or a replacement for shotguns, submachine guns and carbines of pistol caliber in the squad car - the P90 seems to hold a great deal of potential for law-enforcement applications, especially when equipped with the outstanding Gemtech P90 suppressor. Fabrique National Herstal SA of Belgium is now entering the law-enforcement market.

The Gemtech SP90 suppressor removes more of the high-frequency noise than the typical suppressor designed for intermediate rifle cartridges, so the lower pitch sound signature of the Gemtech suppressor actually seems quieter to people with a normal range of hearing than the numbers in Table I would otherwise suggest. The Gemtech SP90 suppressor provides excellent sound reduction, no adverse effects on reliability or accuracy, a relatively light and compact package, and superior durability when subjected to full-auto fire compared to previous generations of suppressors. The Gemtech SP90 represents an impressive, state of the art suppressor, and I can recommend it enthusiastically. [It is available exclusively from FN Manufacturing, Inc.]

Suppressor performance was determined by measuring sound signatures using the equipment and procedures specified at the end of Chapter 5 in the book Silencer History and Performance ($55 postpaid, Wideworld, Dept. SAR, P.O. Box 1827, Conway, AR 72033). The microphone was placed 1.00 meter to the left of the suppressor or muzzle according to U.S. Army testing procedures specified in MIL-STD-1474C. The ambient temperature during the testing was 73°F (23°C), and the speed of sound was 1,132 fps (345 mps). Velocities were measured in feet per second using a P.A.C.T. MKIV timer/chronograph with MKV skyscreens set 24.0 inches apart and the start screen 8.0 feet from the muzzle (P.A.C.T., Dept. SAR, P.O. Box 531525, Grand Prairie, TX 75053, 214-641-0049). Atleast 10 rounds were fired to obtain an average sound signature or muzzle velocity.

Two kinds of 5.7×28mm ammunition were used for the study. The supersonic SS190 round has steel core in front of an aluminum core toward the base, a projectile weight of 31.0 grains (2.02 grams), and a nominal published velocity of 2,345 fps (715 mps). The subsonic SB193 round is a lead core boat tail with a length of 0.753 inches (19.1 mm) and a projectile weight of 55.0 grains (3.58 grams) in front of 2.0 grains (0. 13 gram) of ball powder. The SB193 round is still under development at the time of this writing, and an improved variant of the subsonic round is scheduled for field trials in the spring of 1998. Therefore, any data reported here on the subsonic round must be regarded as provisional.

The sound signatures, which are more properly called sound pressure levels (SPLs), appear in Table I along with some comparative data for reference. Since the FN P90 might compete against both 5.56×45mm and 9×19mm weapons for law-enforcement applications, data on both categories of weapons are included. Unsuppressed and suppressed versions of the M4A1 were tested at 50°F (10°C). The MP5 and MP5 SD were tested at 71°F (22°C). Unsuppressed and integrally suppressed .22 rimfire rifles were tested at 83°F (28°C) to provide a baseline for sound signatures significantly less than normally encountered in the tactical environment. The net sound reductions appear in Table II. Figures 1-3 compare aspects of the extemal ballistics (velocity, trajectory and bullet drop) produced by the SS190 FMJ round fired from a P90, a Winchester USA 9x 19mm FMJ round with a 115 grain (7.48 gram) FMJ projectile fired from an H&K MP5 submachine gun, and an M855 5.56×45mm round with 62 grain (4.03 gram) projectile fired from an M4A1 carbine. The P90 produces a projectile velocity that falls in between the M4A1 and MP5 and provides performance reminiscent of (but a bit less than) the venerable old .22 Hornet, which was used in several survival weapons once issued to the U.S. Air Force. Thanks to the fairly brisk muzzle velocity and the P90’s high sights, Figure 2 shows that the P90’s trajectory is remarkably similar to the M4A1 out to the P90’s effective range of 150 meters (137 yards). Clearly, an operator of average skill will obtain much better hit probability or shot placement with the P90 than with the MP5 simply because of the flatter trajectory provided by the SS190 round.

Mounting a suppressor on the P90 does have an effect on projectile velocity. The SS190 round produced a muzzle velocity of 2,339 fps (713 mps) when fired without the suppressor mounted on the P90 and 2,262 fps (689 mps) when suppressed. The SB193 subsonic round produced a muzzle velocity of 998 fps (304 mps) without a suppressor and 951 fps (290 fps) when the suppressor is mounted. Velocities decrease slightly when the suppressor is fitted to the weapon since the increased back pressure causes the blowback bolt to begin extraction sooner after ignition than the unsuppressed weapon. As Figure 4 shows when comparing bullet trajectories of suppressed versus unsuppressed P90s, this slightly reduced velocity when the suppressor is mounted has almost no effect on practical external ballistics when using the standard SS190 supersonic round, and should have even less effect with the subsonic round since there is sig-nificantly less velocity change in suppressed versus unsuppressed mode. A discussion of terminal ballistics is beyond the scope of this study. From an operator’s point of view, however, there are a number of conclusions to be drawn about the P90 Personal Defense Weapon and the Gemtech P90 suppressor designed for the weapon.

From: http://www.remtek.com/arms/fn/p90/index.htm