Thursday, January 31, 2008

MGD / ERMA PM-9 submachine gun (France)

7,65mm MGD submachine gun (possibly prototype) with fixed wooden stock

9mm MGD PM-9 submachine gun in ready position, right side

9mm MGD PM-9 submachine gun in ready position, left side

9mm MGD PM-9 submachine gun in folded position

Close-up view on receiver of MGD PM-9, with rotating charging handle and folding magazine housing

Author demonstrates the compact size of MGD PM-9 submachine gun in folded configuration

Drawing from original US patent, issued for design of the MGD submachine gun

Caliber 9x19mm Luger / Parabellum
Weight 2,53 kg empty
Length (stock closed/open) 359 / 659 mm
Barrel length 213 mm
Rate of fire 750 rounds per minute
Magazine capacity 32 rounds
Effective range 100 meters

The MGD PM-9 submachine gun was developed during late 1940s and early 1950s by frenchman Louis Debuit, who at the time worked for French company Etablissements Merlin & Gerin in Grenoble. The idea behind this unusual and little-known weapon was to provide a compact and easily concealable weapon with low felt recoil. Apparently, the MGD name comes from names of the company (Merlin & Gerin) and name of designer (Debuit). Early prototypes were made in French 7,62x20 Long caliber, but later development switched to 9x19mm caliber weapons. M & G built undisclosed numbers (probably several thousands) of MGD PM-9 submachine guns in several modifications, including versions with fixed or folding stocks, and with standard (short) or quite long (rifle) barrels, all between 1954 and 1955. In about 1956, German arms company Erma Werke tried to produce 9mm MGD PM-9 submachine gun under license from Merlin & Gerin. According to available sources, Erma produced about 10 prototypes of MGD, and then switched to other designs, which were less complicated to make and thus less expensive. Actually, what killed this interesting weapon was it expensive construction, which required a lot of milling and other labor-extensive metal processing. It is not known if these weapons were ever issued to any military or police service, or participated in any military conflicts.
Author was able to examine one of MGD PM-9 submachine guns, and it was surprisingly devoid of any markings, and its history was unknown.

MGD PM-9 submachine gun is deleayed blowback operated weapon which fired selectively in single shots or full automatic mode, from open bolt. The most unusual design solution was very light and compact bolt (breechblock), with additional mass provided by rotating flywheel located in the circular extension on the right side of the receiver. The flywheel was connected to the clockwork-type spring, and had a projection on one side, which entered the vertical cam track, cut in the rear extension of the bolt. To cock the gun, shooter has to rotate flywheel for about 180o counterclockwise (looking from right side of the gun) through the handle which is located on the right side of the gun. Once wlywheel is fully rotated back, it is locked there by the sear. This cocking movement also pulls the bolt back. Upon firing, the pull on the trigger releases the flywheel, and its spring rotates flywheel clockwise, thus pushing the bolt forward, to load the fresh cartridge from magazine and then fire it once the cartridge is fully seated in the chamber. Upon discharge, the rearward movement of the bolt is delayed by inertia of the flywheel, the force and the spring, combined with the leverage, provided by the position of the pin on the flywheel relative to the axis of the flywheel.
Other features of MGD included a folding magazine housing (which received widely available MP38 / MP40 magazines of German origin), and a side-folding stock, made from thick steel wire. The sights were of simple fixed variety, set for 100 meters range.

Tuesday, January 8, 2008

TDI Kriss Super V™ submachine gun (USA)

TDI Kriss Super V™ submachine gun, prototype

TDI Kriss Super V™ submachine gun, prototype, disassembled into basic components

Prototype Kriss Super V™ submachine gun is being fired by Tom Maffin of TDI

Diagram from US patent application which depicts the basic Super V™ action of the Kriss submachine gun.

Caliber .45 ACP
Weight, empty 2,18 kg prototype
1,8 - 2,0 kg target for production gun
Length (stock folded / opened) 406 / 635 mm
Barrel length 140 mm
Rate of fire 800 to 1100 rounds per minute
Magazine capacity 13 rounds (28 round magazine is being developed)
Effective range 100 meters

Kriss Super V™ submachine gun is an interesting experimental weapon which is currently (spring 2007) under advanced stages of development. The name Kriss comes from Indonesian sword or large knife with flame-like blade. This weapon is intended to provide operators with improved control over accuracy and bullet dispersion, in both semi-automatic and full automatic modes, while firing hard-hitting .45 ACP ammunition. The overall design also permits the Kriss to be fired single-handedly when required by tactical situations and with adequate accuracy. To achieve those goals, Kriss Super V™ submachine gun employs three basic solutions. First is to place the axis of the recoil force in line with the firing hand, thus minimizing the muzzle climbing. Such system was previously employed in Olympic-class small-bore pistol developed in Russia and was subsequently banned from international ISU competitions because of extremely high accuracy, which made completion "unfair". The second solution is probably more novel, as it uses a laterally moving weight, attached to the breechblock (bolt), to divert recoil forces to the bottom direction. The third solution is actually a part of the second system, and it employs a variable-angle track in the weight (#510 on diagram above), which puts a breechblock at a mechanical disadvantage during earlier stages of recoil, thus slowing down the movement of the bolt while pressure in the barrel is still high. As a result of these measures, Kriss Super V™ submachine gun has significantly less muzzle climb when compared to most modern submachine guns. This results in better accuracy and better grouping of hits on target, providing operators with greater lethality during short-range and short-time encounters.

According to the manufacturer, the Transformational Defense Industries, Inc. (TDI), a wholly-owned US subsidiary of the Gamma Industries (Switzerland), the Super V™ system also can be used for submachine guns in other calibers (i.e. 9mm Luger and .40SW). TDI is also developing civilian-legal semiautomatic carbines with 16" (405 mm) barrels. To date (April 2007) TDI has manufactured four prototypes of the Kriss Super V™ submachine guns, which displayed very promising results during numerous live-fire tests. The development of selective-fired version of Kriss Super V™ weapon is conducted in cooperation with US Army ARDEC and several undisclosed industry partners.

Kriss Super V™ submachine gun is delayed blowback operated, selectively fired submachine gun. It fires from closed bolt for enhanced first-shot accuracy. Fire control group is situated above the barrel. Very light bolt is connected to the vertically sliding weight, which is located within a polymer housing in front of the pistol grip. In one of tested configurations additional Enidine hydraulic buffer assembly is employed to further decrease rate of fire by about 200 rpm and to lower weight of the moving parts. Folding cocking handle is located on the left side of the gun, and does not move when gun is fired. Firing controls include ambidextrous fire mode selector switch, located about the middle of the upper receiver / trigger mechanism housing, which provides full auto fire, 2-round bursts and semi-automatic fie, and a separate ambidextrous manual safety switch, which is conveniently located just above the pistol grip. Feed is from 13-round Glock Model 21 magazines, but a larger capacity, 28-round magazine is currently in development. Magazine is inserted into a housing, located in front of the pistol grip. Kriss Super V™ submachine gun is fitted with two Picatinny type rails, one above the receiver and another below the barrel, and two additional rails can be installed on either side of the lower receiver, providing ample mounting space for all necessary accessories, such as laser-aiming modules or tactical flashlights. The upper rail can accept a variety of sighting devices, such as open or red-dot sights; lower rail is usually fitted with vertical foregrip. On latest prototype, the front of the upper receiver / trigger housing above the barrel is hollow and shaped as to accept tactical flashlight. A side-folding polymer buttstock is provided for more accurate shooting.

Kel-tec RFB rifle (USA)

Kel-tec 5,56mm SUB-16 prototype personal defense weapon of early 1990s, which served as a starting point for RFB

Kel-tec RFB 'Target' rifle with heavy-profile 32-inch barrel, telescope sight, folding bipod and 10-round magazine

Kel-tec RFB 'Carbine' with 18-inch barrel, 20-round magazine and red-dot sight, compared to FN FAL Para rifle.

Kel-tec RFB rifle partially disassembled

Diagram displaying forward ejection system of the Kel-tec RFB rifle

Bolt of the SRT-8 (Kel-tec RFB prototype) rifle, with cartridge held in upper (ejection) position by dual pivoting extractors / ejectors.

RFB Carbine RFB Sporter RFB Target
Caliber: 7,62x51mm / .308 Winchester
Barrel length 457 mm / 18" 610 mm / 24" 813 mm / 32"
Overall length 661 mm / 26" 813 mm / 32" 1016 mm / 40"
Weight, unloaded 3,67 kg / 8,1 lbs 3,95 kg / 8,7 lbs 5,1 kg / 11,3 lbs
Magazine capacity 10 or 20 rounds

The RFB rifle is a very interesting development of the Kel-tec CNC Industries company, USA. First displayed during ShotShow 2007 expo, this weapon is now (spring 2007) in advanced development; mass production scheduled to early 2008. The RFB is an acronym which stands for Rifle, Forward ejection, Bullpup. It is a brainchild of the George Kellgren, the chief designer of the Kel-Tec. George Kellgren was long involved into development of advanced bullpup rifles, starting with unorthodox Interdynamics MKR rifle of late seventies. During following decades, Kellgren designed a number of bullpup weapons, featuring first bottom and then forward extraction. During early nineties Kellgren designed a compact bullpup 'personal defense' weapon, designated SUB-16. This was a gas-operated semi-automatic weapon, firing .223 Remington ammunition and featuring forward ejection, with dual tilting extractors / ejectors used to move fired cartridge up from the breech face and push it into ejection chute above the barrel. SUB-16 was a promising and really novel design but the infamous Assault Weapons Ban of 1994 effectively has killed it. Nevertheless, the forward ejection concept was not forgotten, and in around 2003 Kel-tec initiated development of an accurate, semi-automatic rifle with long barrel and compact bullpup layout. In 2005, Kel-tec team began development of the SRT-8, the 7,62x51 semi-automatic sniper rifle. After much experimentation Kel-tec team successfully solved most problems associated with forward ejection system, and in November 2006 the SRT-8 project has changed its name to RFB. Original model designations 'Sniper', 'Hunter' and 'Battle' were also changed to less menacing 'Target', 'Sporter' and 'Carbine' respectively. As of now (April 2007), Kel-tec is tooling up for first pre-production batch of RFB. At the same time, Kel-tec is investigating smaller- versions of the same design, adapted to 'intermediate' calibers such as 7,62x39, 5,56x45 / .223, 6,5 Grendel or 6,8x43 Rem SPC. This weapon will be significantly lighter and more compact, retaining same ambidexterity and high barrel length to overall length ratio of the RFB.
It must be noted that at the present time the only fully ambidextrous bullpup rifle with forward ejection is the Belgian FN F2000 assault rifle and its civilian derivative FS2000, both available only in 5,56mm / .223 caliber.
The key advantage of the RFB is that it provides a compact and fully ambidextrous package, combined with increased barrel length, thus allowing for increasing ballistic performance using same cartridge (as compared to rifles with traditional layout).

Kel-tec RFB rifle is gas-operated, using short-stroke gas piston located above the barrel. Gas system is fitted with manual gas regulator, located at the front of gas block. Bolt system is somewhat unusual, as the long bolt carrier has an inverted U-shaped cross-section, and runs above the barrel and ejection chute. The bolt is hinged to the rear of the carrier. Locking is achieved by tipping the rear of the bolt down, to engage locking recesses in barrel extension. Forward ejection system includes dual extractors / ejectors, pivotally attached at either side of the bolt. Upon final stage of the bolt opening movement, those extractors are cammed up, to bring the fired cartridge above the barrel and in line with ejection chute above it. Upon closing movement of the bolt, it strips the fresh cartridge from magazine and feeds it into the chamber, simultaneously pushing the fired case forward and into ejection chute. Upon final closing movement of the bolt ejectors are cammed down to release fired case and to grip on the base of the fresh cartridge in the chamber. Fired cases then remain in the ejection chute until manually shaken out of it or pushed out by subsequent cases. Special provisions are made to avoid empty cases bounced back from chute and into receiver. Bolt system features dual return spring installed on captive spring guides. Upon disassembly, bolt group along with recoil springs is removed from the gun as one unit. Charging handle is reciprocating and can be installed on either side of the gun.
The rest of the gun is mounted on the barrel, which forms the backbone of the weapon, using four captive cross-pins. Forend, pistol grip / trigger pack / magazine housing and receiver cover / buttstock are made from impact-resistant polymer. Basic disassembly of the RFB requires no special tools other than a cartridge or other pointed object, which is used to push out connecting pins.
Firing unit is hammer-fired, and features an interesting system which provides consistent and crisp trigger pull. In essence, this system keeps the sear next to the trigger, and the necessary long linkage is located between sear and hammer, not impairing the trigger pull. The trigger is fully adjustable. Manual safety levers are located above pistol grip at either side of the gun. Feed is using "metric" FN FAL magazines, which are readily available on the market. There are no open / iron sights as standard on RFB rifles; instead, a Picatinny-type rail is rigidly attached to the barrel. This rail will accept any sighting equipment with appropriate mounting interface.