Bofors – Small Arms Review

Kulspruta Model 1936 in the Fiftieth State

SAR Staff — Thu, 01 Mar 2001 21:25:00 +0000

By Mark Genovese

I’m sure all of you guys out there are saying to yourself, what the hell is a Kulspruta and why is it in a non free zone state like Hawaii??? The Tung Kulspruta or heavy machine gun, until very recently was the Swedish front line water cooled, in caliber 8×63 Swedish, the so-called Bofors round which has recently begun to appear in this country as a specimen cartridge for collectors.

Although the inside dimensions of the receiver and the gun’s crudely cast brass trunion are very similar to the Browning 1917 water-cooled, there are many other differences. The gun uses a spring-loaded non-reciprocating type cocking handle and an incredibly complex, overly engineered recoil-buffered gun attached cradle. The spade grips are not part of the gun itself, but are mounted to the rear of the cradle with what appears to be an articulated linkage, which will trip the sear, so during firing the gun moves back and forth within its cradle while the gunner’s hands are stable. With its tripod at 55 pounds, the whole affair weighs in at a whooping 113 pounds without water or ammunition. Unlike the Browning, the Model 36’s steam will exit the gun via the bottom of the brass trunion and it has only one filling port, with no provision under the water jacket to completely empty any remaining water after firing.

The Swedes have taken a simple and reliable Browning idea, over complicated everything they can get their hands on and then forgot the drain plug? To make matters worse, the fill port tube is recessed within the water jacket. This means that even if you were to hold the gun upside down to drain the remaining water, there will always be some left, unless you siphon it with a small rubber hose. This may not sound like a big deal, but it evidently was back then.

Just before I took my long awaited beautiful remanufactured Kulspruta out to test fire at the Ukumehame firing range, it was laying in its gun case on the floor and my eye caught an almost microscopic 8” long set of red lines on the bottom of the water jacket, up front right where the drain plug should go. I got out my trusty magnifying glass, only to realize these odd red lines were cracks right through the water jacket.

Needless to say, my heart sank. At first I thought the gun’s jacket was made of cast iron and perhaps had been violently thrown to the ground. For some reason the cracks’ strange pattern looked vaguely familiar. The best thing for me to do was call my good friend Stan “The Man” Andrewski of Webster, New Hampshire. He is arguably the best Class 2 manufacturer and gunsmith on the planet.

Just home from the April 2000 Knob Creek shoot and very road weary (plus a sight more broke), it took ol’ Stan all of about two seconds to diagnose the Kulspruta. “The gun is from Sweden, right? They left water in it and it froze.” No wonder the crack looked familiar, as a plumber on the mainland many years ago ninety percent of my winter work was fixing frozen pipes. Stan said the faster you get it here the faster it will get done. With that statement I immediately sent out a Hawaiian care package, two pounds of fresh Kona coffee beans, one extra large local style tee shirt and the gun of course.

Other differences from the Browning would be that the water jacket is slightly shorter in length due to the trunion and its wide tapered brass extension collar, which enhances the aesthetic value of the gun. Also the water jacket has a magnificently engraved royal crest. With a large Schwarzlose type cone flash hider and deep blue finish, this piece is a real looker and rare indeed. I have yet to find even one word about it in print in all my literature. A good friend came to the rescue with a copy of a Kulspruta manual, mostly in Swedish and for the air-cooled model, but a Godsend nonetheless.

This project started at Knob Creek in April 1998, talking with machine gun Dave of Sarco Inc., Sterling, New Jersey. He casually mentioned he had several of these oddball Swedish water-cooled kits he thought were very similar to the 1917 Browning design. Later that month, I talked with my very favorite lady friend and talented inventor/ gunsmith, Valerie Johnson of Valkyrie Arms, Ltd., Olympia, Washington about doing the work. Apparently she also thought it was a good idea and bought every kit Dave had. There would be serious custom fitting in some areas before this project was over.

For starters, the 8×63 Swedish barrel is a larger diameter than the .30-06 1917 Browning barrel we would have to use, requiring a new design for the front water-packing gland. This was beautifully executed by machining an oversized brass doughnut, the male end threaded to the gun, the smaller female end threaded for a normal 1917 packing gland nut. The kit would also need a 1917 type top cover and ladder sight, very rare and hard to find. Thanks to our friend Mr. Bob Landies of Ohio Ordnance Works, Inc., Chardon, Ohio, who came through with flying colors and believe it or not, it was brand new in the box. Although the brass trunion would accept stock right and left Browning side plates, the original Kulspruta had no pintle bolthole. As noted above, it utilized a buffered cradle. The bottom of the trunion protruded into the area of the new pintle bolt requiring Valerie to drill through what she thought was a solid brass trunion. It turned out to be a hollow interior. To keep water from leaking through these holes, a tube was fitted and welded on both side plates. The complete front sight and the brass threaded filling port plug were missing as well and required manufacturing from scratch.

Since a 1919 left side plate was used, welding and dressing of the three original sight bracket holes would be mandatory. The remainder of the conversion was achieved with Valerie’s stock semi 1919 parts she’s so well known for. Her right side plate is thicker than a full-auto, requiring the bolt, barrel extension and lock frame to be extensively machined to fit the tighter tolerances. The real heart of her semi conversion is the trigger lock group – this is poetry in motion, pure and simple. Starting with a solid block of 4140, a new trigger lock is fashioned to accept a modified AR15 hammer, an unmodified AR15 disconnector and AR15 trigger. A new pivoting sear trip is also used. What you end up with is the exact trigger pull as your tried and true, run forever old friend the AR15.

This will be my third Valkyrie Arms gun. My 1919A6 in .308 has over 20,000 rounds through it. Twice, using a Pact timer, I fired in excess of 650 rounds per minute in semi auto, and never ever had a problem, period. It’s the same with my 1917A1 water-cooled – about 10,000 rounds without a glitch. Although Dave from Sarco Inc. has an original complete Kulspruta tripod and cradle, it is of no use to me, because with Browning side plates and pintle it no longer functions within the cradle. To get over this hurdle, I purchased one of the Stembridge 1917 tripods from the good folks at Long Mountain Outfitter, Harmony, Maine and a D37915 elevator for anti-aircraft use from Hayes Otoupalik in Missoula, Montana. The cherry on top would have to be the spade grip assembly from Ohio Ordnance Works, Inc.

The deep perfect engraving KULSPRUTA MODEL 36 on the upper rear of the right side plate, in my opinion is a work of art Aloha nui loa from upcountry Maui.

This article first appeared in Small Arms Review V4N6 (March 2001)

SAAB Bofors Dynamic’s CBJ MS PDW

SAR Staff — Thu, 01 Feb 2001 21:01:20 +0000

By Charles Q. Cutshaw

Personal Defense Weapons (PDWs) are a current small arms “hot ticket,” especially with the British Ministry of Defence’ recent solicitation that could result in the purchase of some 15,000 PDWs. Although several small arms manufacturers have submitted samples for the competition, one of the more interesting ones was recently shown at the National Defense Industrial Association’s annual Small Arms Conference in Indianapolis, Indiana. Saab and Bofors are both well – known in the defense industry, but not in the small arms field. In this case, however, the two firms have joined forces to produce a dual – caliber PDW for the British competition and for other military and police organizations seeking PDWs.

The CBJ MS is chambered for the traditional 9x19mm pistol cartridge, but by changing barrels can also fire the new 6.5x25mm CBJ cartridge. The 6.5x25mm cartridge is dimensionally identical to the 9x19mm, so the little CBJ MS PDW can use the same magazines and bolt, as cartridge head diameter is also the same with both cartridges. The 6.5x25mm cartridge was developed specifically to meet the NATO CRISAT body armor defeat criteria and according to Bofors representatives, does so to a range of 400 meters. The round also defeats light vehicle bodies. The round itself consists of a 25mm bottlenecked cartridge case and a bullet with a small 4mm diameter saboted tungsten carbide penetrator weighing 2 grams. The penetrator is carried in a plastic sabot that peels away shortly after the projectile leaves the muzzle of the PDW. Performance data regarding this cartridge can be found at Table 2. The ballistic data are extrapolated from manufacturer’s information via a ballistic computer model that has proven to closely real world external ballistic performance. Although the 6.5 CBJ cartridge is claimed to be effective to a distance of 400 meters, realistic engagement distances for PDWs are less than 100 meters; hence our data use that as a maximum.

The CBJ PDW itself is of fairly conventional design, resembling several existing submachine guns in overall design and configuration, but with several innovative features. Operation is blowback, but with two options – either open bolt firing with fixed firing pin or closed bolt firing with floating firing pin. The latter option should prove to be more accurate and possibly more reliable, but only extended testing will establish the overall performance levels of the CBJ MS. The CBJ MS is equipped with a titanium suppressor as standard for use with 9mm ammunition. The CBJ MS also has an optional grenade launcher and Bofors is developing fin stabilized rifle grenades for the weapon. The grenades are launched using standard 9mm or 6.5mm cartridges and include HE, HEAT, smoke, tear gas or flash/bang types. Magazines of 20, 30 and 100 rounds capacity are available. The latter magazine is a drum type that is only slightly longer than the standard 30 round magazine. Bofors provides both types of ammunition in clips of 30 rounds for rapid magazine reloading. The CBJ MS feeds via a magazine inserted in the pistol grip with a spare magazine carried in the forward pistol grip. This provides for quick magazine changes in fast-moving combat situations. The forward pistol grip incorporates a curved guard to prevent the “off” hand from overriding the grip and covering the muzzle of the weapon. A MIL-STD-1913 rail is fixed to the top of the receiver for mounting optics. The standard CBJ MS optical sight is the Trijicon 1.5×24. Open sights are a post type front sight with tritium insert, adjustable for elevation and a three position rear sight that is adjustable for windage. According to the manufacturer, the CBJ MS can also be used as a light support weapon (LSW) and to that end, a bipod is provided as standard. We believe that use of such a weapon as an LSW is somewhat ambitious, given the ballistics of the ammunition and inherent accuracy constraints of weapons of this nature. Again, only extended testing will confirm or deny the manufacturers’ claims in this regard. The CBJ MS also is provided with a small bag that attaches to the receiver to catch spent cartridge casings, a highly unusual accessory in a tactical firearm. “Brass bags” are usually associated with training environments where expended casings must be gathered before leaving the range. In this instance, however, the manufacturer emphasizes the capability of the bag to be quickly emptied in action.

The SAAB-BOFORS 6.5x25mm… Top: Complete round. Overall length and case head diameter is identical to the x19mm. Center: 6.5mm Sabot Bullet Bottom: 4mm Tungsten Carbide projectile. Photo by C. Cutshaw.

It is impossible to accurately assess a firearm without actually firing it and SAAB Bofors unfortunately did not have any fully functional examples of their new PDW at the NDIA Small Arms Conference. Extensive “hands-on” examination of the CBJ MS while at the SAAB Bofors display booth, however, gave a favorable first impression of this latest PDW. Controls are well – placed and their use is obvious after a quick cursory examination of the weapon. We were able to operate the bolt, selector, magazine release and extend and retract the stock without coaching from SAAB Bofors representatives. The little PDW balances and points well, but only time and actually testing the CBJ MS on the range will tell if these general first impressions carry over into actual functional usage of the SAAB Bofors CBJ MS.

SAAB-BOFORS 6.5x25mm CBJ MS PDW. Photo by C. Cutshaw.

This article first appeared in Small Arms Review V4N5 (February 2001)

The AT-4 Launcher

SAR Staff — Sun, 01 Oct 2000 20:20:37 +0000

By Christopher Trumble

There have been a number of expended AT-4 launchers sold at Army surplus stores and gun shows to people that have an interest in having an instant conversation piece. For those that have one and do not know anything about their history and use, here are some bits of trivia that you can rattle off.

The AT-4 is a lightweight improved version of the M72 series of light anti-armor weapons that were designed in the early 1960’s. It was determined that there was a requirement for a more powerful version of the 66mm M72. In the late 1980’s the AT-4 was designed and manufactured by Bofors of Sweden (formerly FFV) for use against the improved armor of the current light armored vehicles. In the United States it is commonly referred to as the M136 and manufactured by Alliant Techsystems Incorporated in Minnesota. It is in service with the U.S. Army, Navy, Airforce and Marine Corps.

The primary components of the weapon are the barrel, muzzle cover, firing mechanism, the sights and the projectile. The barrel is a composite glassfibre reinforced plastic that has an aluminum venturi at the exhaust end. The muzzle cover is rubber and acts as a shock absorber. The firing mechanism is a simple spring-loaded bolt-like device that is pushed forward until it locks in place, readying it for firing. The adjustable sights are simple and rugged, utilizing spring loaded polymer panels factory preset to 200 meters, that are stored beneath sliding polymer covers that are meant to protect the sights during transport and storage. The projectile is what is referred to as an 84mm HEAT (High Explosive Anti-Tank) round.

The 84mm HEAT round is composed of a cartridge case and the HEAT shell. The HEAT shell has four primary components, these being the fin assembly, base fuse, stand-off cap and HMX/TNT hollow charge. Upon discharging the HEAT round, the fins open to stabilize the rocket in flight. The fuse is constructed with an out-of-line detonator safety device that prevents accidental initiation. When the stand-off cap portion has traveled a minimum of ten meters (thirty-three feet) and it impacts the target, an impact sensor activates the fuse which in turn detonates the HMX/TNT hollow charge. The result is tremendous behind armor damage that is a combination of overpressure, intense incendiary effects and spalling.

The round is quite effective as evidenced by a better than 97 percent close-in armor defeat ratio and in excess of 500,000 units have been produced. This weapon system is in service not only in the United States, but also in the Swedish Army, the Brazilian Army and Navy, Danish Army and the Netherlands.

There are special variations of this weapon produced for training purposes and all weapons are color coded to signify which system you have. A plain black band or a black with yellow band indicates a HEAT round. A gold or yellow band indicates a field handling trainer and no band is indicative of the M287. The M287 is a 9mm sub-caliber trainer that utilizes a reduced powder loaded 9mm NATO (9x19mm, 9mm Parabellum) caliber tracer cartridge (designated M939) that simulates the ballistics of the 84mm HEAT round for training target practice purposes.

This article first appeared in Small Arms Review V4N1 (October 2000)