Sten Mk II submachine gun and magazines.

By Frank Iannamico

During World War II there were an estimated forty-two million magazines produced for the British Sten submachine gun. Today, Sten magazines are very easy to find on the surplus market and usually very inexpensive. Because of their availability and low price, Sten magazines have been adopted for use in a number of modern firearms, both as issued and in modified form. With such a proliferation of Sten magazines one has to wonder just why anyone would choose to make new ones.

During 1940, the British were in dire need of small arms. The British Lanchester submachine gun and its magazine were a close copy of the German MP28 II submachine gun. The reason for choosing that particular weapon was the manufacturing drawings had been made earlier from two weapons that were in British hands. The existing German magazine and the submachine gun were copied instead of designing a new one to save precious time. The German’s MP28II magazine was the same basic configuration later used for their MP38-MP40 magazines. A similar magazine, in a 32-round configuration, was adopted for the British Sten submachine gun for the same reason. The double-stack single-feed magazine design is a configuration that requires a strong spring in order to force the cartridges into a single row at the top. The spring makes the single feed magazine difficult to load by hand, requiring the use of a loading tool, and places a lot of force on the magazine feed lips. The double-stack double-feed design, as was used in the Thompson submachine gun, is far more reliable and much easier to load by hand.

Sten magazines were produced by a large number of contractors and subcontractors. The magazines were fabricated from sheet metal, with the manufacturing process of the body varying slightly by manufacturer. A thick steel collar was spot welded to the top of the magazine’s body to form the feed lips. The floor plate was made of sheet metal and bent to slide onto the rails formed on the bottom of the magazine body. The floor plate was held in place by a protrusion on a plate attached to the bottom of the magazine spring.

Early Sten magazines proved problematic and were redesigned by eliminating the holes in the rear of the magazine (used to determine how many rounds were in the magazine) and adding a cross brace to connect the legs of the follower to keep them from spreading apart and dragging on the magazine body. The new magazines were designated as the Mk2 design. Many of the earlier magazines were upgraded when processed through a British Factory Thorough Repair program (FTR).

The primary contributing factor of the Sten magazine’s functioning problems is the feed lips’ propensity to spread apart when loaded, changing the critical feed angle of the top cartridge. The condition exists because of the stiff spring inherent of the design.

After Market Sten Magazines

This brings us back to the question of just why aftermarket Sten magazines exist. One of the primary problems with original Sten magazines is that they are 70 plus years old. Springs have a finite life, and the sheet metal parts can suffer from metal fatigue and corrosion. The new manufacture Sten magazines are made of modern materials and to closer tolerances than possible during World War II. When the Sten magazine conversions for the M11/Nine submachine gun were introduced, there was a small run of Sten new magazine springs produced in an attempt to make the magazines more reliable. As a general rule, aftermarket magazines are not as reliable as original factory production. However, the reproduction Sten magazines seem to be the exception. Currently there are two known sources for new manufacture Sten magazines.

TAPCO is a well-known wholesale company based in Georgia that specializes in the accessory market for firearms. One of the products the company offers is a U.S. made, 32-round Sten magazine made from a modern composite polymer material. The spring is made of corrosion resistant stainless steel, the floor plate is steel and the follower is made from the same polymer as the body. The magazines were originally designed for MasterPiece Arms’ 9mm Defender Series of semiautomatic MAC type pistols. The Defender pistols were originally designed to use metal Sten magazines, but as suitable surplus magazines could no longer be found in the quantity needed, the Company persuaded TAPCO to manufacture new ones. They also offer a magazine loader, although the magazines used in the evaluation could be loaded with an original Sten box type loading tool. According to their website, all TAPCO products have a lifetime guarantee.

The second source of new manufacture Sten magazines is an online company called KeepShooting.com. The company, in business since 2002, is located in southern Maryland and sells firearms, firearm accessories, military surplus and ammunition. The Sten magazines offered by Keep Shooting are all steel and exact reproductions of the originals. The company website states: “The magazines are guaranteed to fit and function reliably in any Sten submachine gun, including the Sten Mk I and each of its many variants. This magazine is also compatible with the MPA-30. The body of the magazine, which is designed to hold and feed 32-rounds of 9x19mm Parabellum ammunition to your firearm, is constructed from hardened steel that has been fully heat treated. It also boasts a black Teflon-based finish for enhanced protection against rust and corrosion. Additionally, both the steel spring and follower are precision manufactured to provide for reliable feeds on a consistent basis. The Keepshooting.com Sten magazine is a reproduction of the original Sten magazine, which was a direct copy of the MP-38 magazine. As such, it may still suffer from the reliability issues characteristic of the original design, as our modern manufacturing techniques are not capable of correcting inherent design flaws. If properly maintained, your Keepshooting.com Sten magazine should perform well.”

As advertised, the Sten magazines appear to be very well made. The company website lists the manufacturer as the KeepShooting.com products house-brand. Several efforts were made to contact the company by both phone and email to inquire where the magazines were manufactured. No one answering the phone at the company knew the answer, nor could locate anyone that did. There were no replies to several emails. Judging from the construction and finish of the magazines an educated guess would be South Korea, based on features and construction of other magazines known to be produced there. There are some magazines advertised on the Keep Shooting website that specifically state “not Korean made.” The Sten magazines ad on the site did not include that statement. These particular Sten magazines seem to be only available from this company, so not revealing their source is understandable.

The Field Test

Both the TAPCO and Keep Shooting magazines were tested in a British Mark II Sten, Mark V Sten, Sterling and a Lanchester submachine gun – weapons all designed to use Sten magazines. Ammunition for the test varied from reloads to new full metal jacket with a variety of 115, 125 and 147 grain bullets.

Fit

The Lanchester submachine gun could not be used for the operational test because none of the aftermarket magazines being evaluated would fit into the brass magazine well. Original World War II manufactured 32-round Sten and 50-round Lanchester magazines fit with no problem. During World War II, Sten submachine guns and magazines were assembled from parts supplied by numerous manufacturers both large companies and small workshops. As such the parts were made to generous tolerances. To expand the magazine fit-test beyond the four test guns, the new magazines were then checked in several Sten magazine housings from parts sets and the magazines fit with no problem. One of the magazine housings was from a Lanchester part set. The Keep Shooting magazines fit, but the TAPCO mags did not.

Function

As stated earlier, the primary problem with original Sten magazines is the spreading of the feed lips, which changes the feed angle and leads to failure to feed stoppages. Loading the magazines to full capacity will aggravate this condition. If you leave original Sten magazines fully loaded over an extended period of time, you will probably encounter functioning problems. The feed lips of the new magazines were measured and the feed angle checked. The magazines were then loaded to capacity and stored for several months. The magazines were removed from storage and measured again. The feed lips of all the magazines remained in spec. The acid test was to test fire them. Seven of the Keep Shooting and four of the TAPCO magazines were loaded and tested twice. They were fired in two different Sten variants and a Sterling submachine gun. There were a few stoppages encountered in firing 700-plus rounds, but none could be directly attributed to a magazine malfunction.

Summary

The aftermarket magazines functioned very well in the test; they proved to be more reliable than original World War II magazines. The cost of the new manufacture magazines is comparable with original 32-round surplus mags, and there is no storage grease or Cosmoline to remove.

Sources

TAPCO
www.tapco.com/

Keep Shooting
Phone (877) 703-2767
www.keepshooting.com/

One of the many things that seem to interest firearms owners is caliber conversions. Often, the conversions are desired to enable the shooter to fire less expensive ammunition. During the recent “ammo shortage,” .22 caliber rimfire conversion kits became very popular. Another reason shooters like to change calibers is to experience a different “feel” in their weapon. Whatever the reason, many machine gun shooters are drawn to caliber conversions.

A Brief Sten History

During World War II, the Sten “machine carbine” was Great Britain’s answer for an inexpensive weapon that could be manufactured in large numbers in a short period of time. By 1941, the British were no longer able to afford the expensive U.S. Thompson or the indigenous Lanchester. The desperate, cash-strapped government needed an effective, but cheap weapon to arm its troops. The solution to the problem was the utilitarian Sten. The Sten was made in several guises; the most widely produced was the Mark II model, with an estimated three-million manufactured. According to Captain Peter Laidler, British armorer and author of the excellent book The Sten Machine Carbine, the name Sten was derived from the creator’s last names; Colonel Reginald Shepherd and Harold Turpin and the last two letters representing England. The Sten continued to serve in a number of Third World countries long after World War II had ended. The simple design could be easily copied and manufactured by nations having limited industrial capacity.

Modern Stens

The British Sten Mark II, 9mm submachine gun was reproduced in fairly large numbers by U.S. Class II manufacturers prior to the 19 May 1986 government ban on manufacturing. The guns were built from original surplus part sets, using a newly manufactured receiver: these are commonly called “tube guns.” The Sten is very popular today and remains one of the least expensive submachine guns on the market, although they have increased dramatically from their pre-1986 retail price of approximately $250. Original Sten guns are far less common and generally cost substantially more than a “tube gun.” Original Sten guns qualify as Curio and Relics, while “tube guns” do not.

China

During World War II, the Chinese received a number of 9mm Sten MKII machine carbines under Canada’s Mutual Aid Act. Those Sten MKIIs were manufactured at Canada’s famous Long Branch Arsenal. The weapons destined for China were similar to those made for the British and Canadian armies except that they were marked with Chinese characters on the top of the magazine housing. The markings translated to: “Sten hand carry machine gun, Canada manufactured.” The bottom of the magazine housing retained the standard Long Branch markings, in English, normally located on the top of the housing.

During the late 1940s, the Nationalist Chinese began to manufacture their own version of the Sten designated the Type 38. The 9mm Type 38 was similar to the British and Canadian MKII model except it had no semiautomatic feature, a front sling swivel was added and the sheet metal housing covering the trigger mechanism had a triangular, rather than rounded, shape.

Since the 1920s, China had been embroiled in a civil war between Communist forces led by Mao Tse-tung, and the Chinese Nationalist Party led by Chiang Kai-shek, the conflict continued through World War II. The struggle finally ended in 1949, with a Communist victory. During the conflict, all of the Nationalist Chinese arsenals, and many weapons, were captured by the Communists.

With mainland China under Communist influence, they began adopting, and eventually with technical assistance from Russia, began manufacturing Soviet pattern weapons. The ammunition used in Soviet weapons was also imported and eventually manufactured in-country. Despite the influx and local manufacture of weapons, there were still not enough small arms to equip the large Chinese Army. After decades of fighting, China had collected a potpourri of small arms. Most of the weapons were chambered in a number of different calibers making the supply of ammunition to troops in the field a logistical nightmare. The ever resourceful Chinese decided to solve the problem by converting their collection of weapons to the standard Soviet cartridges of the era; for pistols and submachine guns, it was the 7.62x25mm.

The 7.26x25mm Tokarev Cartridge

The Russians first adopted the Tokarev round in 1930 for use in their Tokarev TT-30 and TT33 semiautomatic pistols. The cartridge was copied directly from the German 7.63 Mauser round. The 7.62×25 Tokarev became the standard Russian pistol and submachine gun cartridge during World War II. Its popularity became more widespread after the war, when many European countries came under Communist influence, and adopted both Soviet designed weapons and ammunition. The standard Soviet 7.62x25mm round features an 85.8 grain full metal jacket projectile. The bottleneck cartridge cases on ComBloc 7.62x25mm ammunition were originally made of brass, but copper washed or lacquered steel cases were adopted, to conserve critical metal (brass). The Communists produced tracer, armor piercing and armor piercing incendiary rounds, but these are seldom encountered in the U.S. Some of the cartridges have projectiles made of mild steel; again this was done more to conserve material (lead) than to create an “armor piercing” bullet, despite what the media reports. The projectile’s velocity can exceed 1,600 feet per second when fired from a 10-inch submachine gun barrel, and has a very flat trajectory.

Caliber Conversions

Back in the 1990s, inexpensive kits were available to convert the popular British Sten Mk II submachine gun to fire the Soviet 7.62x25mm cartridge. (See SAR Vol. 5, No. 1, October 2001 issue.) The kits were originally fabricated by the Communist Chinese who wanted to standardize their weapons, many of which had been supplied by their Western World War II allies, to ComBloc calibers. Since the 7.62x25mm round is too long to fit in a 9mm Sten magazine, a modified Type 54 (the Chinese version of the Soviet PPS43) magazine was used. To adapt the magazine to the Sten, the rectangular portion of the Sten magazine housing was cut away, and replaced by a Type 54 housing welded to the remnant of the Sten housing. The standard Sten bolt was modified to work with the Type 54 double feed magazine. The cartridge base measurements of the 9mm Parabellum and 7.62x25mm cartridges were close enough so that no alterations to the bolt face were required. The Chinese conversion, kits like many surplus items that were once common, are now an item that is seldom encountered.

The primary problem encountered with the Chinese conversion kits was that to install the modified magazine housing, the front sight had to be removed. Most Stens have their front sights welded in place. This made the conversion problematic for most who didn’t want to remove the weld primarily because it would damage the finish, and because most Sten front sights won’t stay in place for long without welding.

While the Chinese conversion kits are few and far between, there is a now a new and better solution for those wanting a 7.62x25mm conversion: Sten magazines that have been reconfigured to accommodate the longer 7.62x25mm cartridges. This was done by removing the concave rib at the rear of the original Sten magazines and welding a steel plate over the cavity. The magazines are stenciled on the back 7.62×25. There is a good reason for this and it applies anytime 7.62x25mm barrels are anywhere near 9mm cartridges. A 9mm Parabellum cartridge will chamber in a barrel chambered for the 7.62x25mm round. HOWEVER, a 9mm bullet will not fit down the small bore of a 7.62mm barrel without causing severe damage to the firearm and the shooter.

Instead of the previous method of removing the front sight and exchanging the magazine housing and bolt, all that is needed are a few converted magazines, a 7.62x25mm barrel and lots of ammo. Although the original Sten recoil spring will work, it will eventually be damaged by the increased recoil of the 7.62 round. To solve the problem, there are special springs available that are designed specifically for the 7.62 conversion. The barrels, while still somewhat scarce, could easily be fabricated by a qualified gunsmith.

Despite their reputation, Sten magazines are reliable if a cartridge angle of 8-degrees is maintained by periodic inspection and adjustment. Double stack, single feed magazines are difficult to load by hand, and Sten magazines are no exception. The bad news is that the 9mm British magazine loaders, that make loading almost fun, will not work with the longer 7.62x25mm rounds.

The standard Sten sights are not calibrated for the flat trajectory of the 7.62 ammo, but this generally does not present a problem for most owners, who tend to fire their Stens in more of a point and shoot style. The report and felt recoil of a 7.62x25mm Sten immediately makes the shooter aware that the weapon is not firing 9mm ammunition.

While the supply of surplus 7.62x25mm ammunition seems to come and go, it is currently available and less expensive than 9mm. Most of the ammo is berdan primed and corrosive, not a concern if you clean accordingly. The abundance of this ammunition has created some new conversions; one of the most popular is for the AR-15. Recently, Wise Lite Arms introduced a semiautomatic version of the British Sterling in 7.62x25mm.

Cartridge Comparison(in inches unless otherwise noted)

Sources:

Sten magazines converted to 7.62x25mm
on an exchange basis.
PO Box 258
Boyd, TX 76023
(940) 433-8095
www.wlawarehouse.com/store_front/sterling/7-62×25-mag-conversion/

Special recoil springs for the 7.62x25mm conversion

Scott Andry Machine
108 Beaufort Road
Fremont, NC 27830
(919) 242 6334
scott@samachine.com

7.62x25mm Ammunition

Century Arms
http://www.centuryarms.com/
(800) 527-1252

I.O. Inc
PO Box 847 Monroe, NC 28111
(866) 882-1479

STEN MK II, III AND V RECOIL BUFFER

If you have a Sten, semi-automatic or select-fire or even if you have some Sten parts kits, the STEN Recoil Buffer is a NEW accessory item that will benefit you and your gun! The Sten is already a fairly tame firearm by itself, but with the Recoil Buffer installed, the recoil will feel near to nothing! The shooter should notice at least a 60% reduction in felt recoil and less muzzle climb. It will add life to any Sten by stopping the metal-to-metal contact and wear from the rear of the bolt impacting the return spring housing/cap. The recoil buffer also reduces the noticeable action noise of the Sten. Installation is simple, especially for those already familiar with the disassembly of their Sten. Easy to follow illustrated instructions are included with each Sten Recoil Buffer. Retail price for the new buffer is $5.50 with a special introductory price of just $4.25 each with $3.50 shipping and handling per total order. Also, for a limited time buy 2 and get 1 FREE. For more information or to place an order contact Mark Holloway at 25th CTC (25th Century Today Concepts), Dept. SAR, Rt #1, Box 127C, Griffithville, AR 72060. Phone: 1-870-256-9989. Fax: 1-870-256-4580. E-mail: mjholowy@ipa.net.

STRENGTH-LOCK GUN CASE

The Strength-Lock Case is the first affordable protective handgun case designed specifically to store handguns safely without the use of numbered locks or other keyed entry devices. This case will absolutely minimize the possibility of a handgun being accessed by a child or any other unauthorized user, yet the Strength-Lock case still allows the handgun owner quick access whenever a need arises. The Strength-Lock case utilizes a simple but very effective secret locking mechanism. There are no keys to find or combinations to remember. Special instructions for the secret locking mechanism are easily mastered by the handgun owner and can then be destroyed. As an added deterrent, the technique to operate the locking mechanism requires the strength and manual dexterity of an adult. There are two versions of the locking mechanism. The Strength-Lock Lite is ideal for women handgun owners or for households with only small children. The original Strength-Lock Case is suitable for all other households. The Strength-Lock is the perfect carrying/storage case for handguns. It is strong, durable and stable and will hold handguns with barrel lengths up to 6 inches. This affordable case cushions and protects a handgun while helping to keep it out of a childs’ hands. No product can guarantee to be 100% childproof, but the Strength-Lock Case will significantly limit any child’s ability to access its contents. For more information contact Douglas Industries, L.L.C. Dept. SAR, 2850 East Prestwick Road, Warsaw, IN 46580. Phone: 1-219-269-4959. Fax: 1-219-267-2499.

H&K 91/G3 FLAT TOP RECEIVER

Federal Arms is now selling an all U.S. made H&K 91/G3 style receiver. The receiver is super strong, super light weight and is made entirely of aluminum. Using the same technology as is used in the M-16 rifle receiver the Federal Arms H&K type receiver is precision machined from a solid block of aluminum. The new receiver is said to be 20% stronger than the original H&K receiver. It features a built-in scope rail milled right into the top of the receiver allowing the user to mount optics without the need of purchasing an additional, not to mention expensive scope mount. The receiver is also milled to acccept the original H&K rear sight so the shooter can have either open sights or the use of a scope. It has a pebble grain feel and is finished in a space-age black Teflon coating. The coating offers unrivaled lubricity as well as functional integrity. With the purchase of a readily available parts kit, the receiver allows an entire firearm to be assembled quickly and easily without the need for any welding. The receiver will only accept semi-auto parts as per B.A.T.F. guidelines. Now you can have the H&K style firearm that you thought was gone forever! For more information contact Federal Arms Corporation of America, Dept. SAR, 7928 University Avenue, Fridley, MN 55432. Phone: 1-612-780-8780.