Sten Gun Mk.II Silenced ~ Advice Please

[Salzburg]

I'm just wondering if anybody has, or can steer me in the right direction of, any information on Sten Mk.II Silenced serial numbers and manufacturers please.

Regards

Martin

[Villafuego]

From an archived Small Arms Review article:

"Three main types of Special Sten/Sten Mk.II(S) have been observed in quantity as follows:

First production model silencing units are found on B.S.A. manufactured guns with B prefix in serial number series B 341000, B 360000 and B 363000. The silencing units are two inches in diameter and are not equipped with any web handguards. The insulation is integrated in the silencer between the inner and outer tubes of the silencer. All the weapons observed have had the letter “S” stamped on the bottom of the magazine housing. These Sten guns are typically marked STFN instead of STEN, indicating a worn die used for marking the guns.

The silencer has a number of metal discs in front of the 7.2 inch barrel, which is ventilated with 6 bleed holes. A thick rubber disc is placed at the muzzle of the silencing unit to stop the powder gases from escaping. The effect of the silencing unit decreases as the rubber disc wears out. A number of silencing units have been observed with light bullet strikes at the muzzle, possibly caused by firing in recent times after the rubber had hardened thus diverting the bullets.

The silencing units are serial numbered and observations have been made in a range from 1-3400. It is not possible to say if as many as 3,400 were made but the observed numbers from 1-1500 have been so many that it’s quite possible that this range was filled. A number of these weapons were also equipped with night sights. Guns with night sights had the silencing unit permanently attached to the submachine gun. Most of the observed silencing units with night sights were in the 1-350 serial number range with one exception around serial number 3400. This model appears to have only been used by SOE agents. As mentioned above, these silencing units are possibly the shortened Kulikowski silencing units mentioned in the reports.

Second production model silencing units are found on guns with Serial numbers with TF prefix and a one and a half inch diameter silencing unit with asbestos string as insulation covered by a web handguard. These silencing units have a large threaded front cap in the muzzle that may be unscrewed for disassembly and cleaning. Instead of the metal discs, this silencing unit used a series of baffles stacked in front of the barrel and held in place by the muzzle cap. A felt disc was positioned inside the muzzle cap to help in sealing off the gases inside the silencing unit. The barrel is 3.62 inches long and has 10 bleed holes. The guns and silencing units are numbered to each other and the bolts appear to have been lightened on all the specimens observed. The guns are marked STEN MkIIS and are textbook examples of the official British army Sten MkII(S) as described in books and manuals.

Third production model silencing units are found on Fazakerley manufactured guns with FP prefix on the serial numbers. This silencing unit also has a one and a half inch diameter tube but it is quite different from the previous model. The silencing unit has a collar about one third from the rear where it can be taken apart. Internally it has the same disc pattern as the first production model mentioned above, but it has a number of thin mesh discs in each end of the set of discs. The length of the barrel is 4.75 inches and it has 6 bleed holes. These silencing units were developed by E.S.6(W.D.) and used by the SOE. It appears that this silencing unit is a direct successor of the two inch diameter type. The guns and silencing units are numbered to each other and the serial number on the silencing unit will be found on the side of the tube in front of the web handguard. The insulation is provided by asbestos string, but on this silencer it is covered by insulating tape. The Sten guns do not have any special markings on the magazine housing. As mentioned above, the silencing units are visually very close to the Army Sten Mk.II(S) type and were named “Attachment no.6, Sten Machine Carbine, Mark 1, design E.S.6(W.D.).”

The quantities made of the various models of the Sten gun silencing units are very difficult to make estimates on. As mentioned, the first production model will be found with numbers between 1-3400, but it’s quite possible that only blocks of serial numbers were used. The second production model, the textbook STEN MkII(S), is reported to have been made in quantities of 2,500-6,000. The third production model is just as vague as neither the first nor the third model are often encountered outside Norway where they were sent by the SOE. It is probably safe to assume that the total number of silenced Mk.II Sten guns lie somewhere between five and ten thousand guns total.

[Andersen75]

who knows, thes bronze bolt from sten silenced?

[Villafuego]

who knows, thes bronze bolt from sten silenced?

That's a standard bronze bolt......

here is a bolt from a Mk2 S

[Torch]

Ive never seen a bolt like that villafeugo..seems odd to have a bolt like that in a silenced weapon..being so much lighter than a standard bolt the cyclic rate would have been higher leading to higher silencer unit temps even at bursts..unusual

[AZPhil]

A lighter bolt (Hence the slimmer brother)means less time in Battery which would be less pressure and a slower bullet eliminating the sonic crack a normal round would cause when it exceeded the that limit. This would also decrease the pressure build up when it would exit the barrel. This is the other formula that needs to be addressed when trying for mouse fart silence and then all you hear is the bolt slamming into the breech. TICK TICK TICK.

Those bolt's are obviously from places that neuter their weapons because those bolt faces make we want to shed a tear.
Semper Fi
Phil

[Torch]

Curious,ive never heard that theory before as a bolt still needs to remain in place long enough for chamber pressure to drop to a safe level before it starts to travel rearwards,opening of the breech before the pressures have dropped to a safe level has a few adverse effects one of which is driving the bolt back faster than was ever intended and faster than the recoil spring is able to handle also the sten was never equipped with a buffer which would end in weapon damage as the bolt meets its reward position far quicker than it was designed..the reduction in bullet velocity you speak of is needed in silenced weapons but every model of silenced sten had bleed ports drilled just forward of the chamber to reduce muzzle velocity to subsonic before the projectile entered the silencer unit so a lighter bolt is certainly not required in this weapon and the problem of increased cyclic rate through a silencer unit still remains

[AZPhil]

Very Good point Torch. If you lighten the bolt you will increase the rate of fire if you are using stand load ammo and it will damage the receiver(Crack) if a buffer is not installed. But now my experience is just having the privileged of being the tester on several "Experiments" using the Uzi as the test bed. Some of the test/mod's were run by a SOT and the other by a silencer baffle designer. Both legally licensed to do so. I do not have experience with the silenced sten so I can not comment on that. But with the heavy bolt on the uzi the rate of fire drops several RPM when using sub sonic ammo. The test included stock reduction(Holes drilled into the bolt) and also a bolt made from titanium. Which cost a pretty penny. The two issues that were addressed were the concern for out of battery discharges. In which Several time's the rim of the casing blew out when out of battery and mags blew out the bottom, top cover bent and I got powder burns. But the timing issue was addressed and fixed. Note! When I said privileged I should have said test dummy. The next was to maintain the original rate of fire while using rounds that were sub sonic( reduced powder loads to reduce the FPS) and the lighting of the bolt while still keeping the original recoil spring was the answer.

Semper Fi
Phil

[Villafuego]

The lightened bolt was actually required for the Mk2S to function at all......due to the extensive bbl. porting (to reduce the projectile to subsonic velocity), there is simply not enough backpressure generated to cycle a standard weight bolt.

Sten "speed bolts" are commonly made.....along the patterns of the original Mk2S bolt....and in a standard (unsuppressed) Mk2 will raise the rate of fire up to around 750-800rpms.

The cyclic rate of an original Mk2S (with the lightened bolt) is about the same as that of a standard, unsuppressed Mk2 (with standard weight bolt). The delay in breech opening for both guns is virtually identical....

Original Mk2S's really can't be compared to other suppressed SMG's, as most others do not use a ported bbl, and rely strictly on downloaded propellant charges and heavier projectiles to achieve subsonic velocities....and since most suppressors actually increase backpressure, the ammunition used usually has to be substantially "downloaded" before you see a decrease in the rate of fire, or develop issues with bolt weight, or spring rates.....

Running standard velocity 124gr ammo in my Uzi, there is about a 100 rpm increase with the suppressor attached.
Using 158gr subsonic ammo with the suppressor attached, there is a negligible increase in the rate of fire.....although it will progressively speed up as the pressure in the suppressor increases (L34A1 Sterlings tend to do this as well)...
Using 158gr subsonic without the suppressor makes it sputter like a M3 greasegun....with the occasional failure to eject........

[m3bobby]

The bronze bolt is an economy bolt and didn't last very long due to ware on the bent. They aren't actually bronze but are an alloy of Aluminium and Bronze and aren't really suitable for modern STEN shooters and are more of a collectable.