Specialized Sten Barrels

Over the years I've acquired a couple of 9mm Sten barrels that I can't identify. Have checked Peter's book and the other Sten references in my library and online. I suspect they were for WW II suppressors, but don't match the drawing in Peter's book. They're not threaded, so I doubt they're related to postwar cans.

Can anyone confirm what the two specialized barrels in this pic were for? (The bottom barrel is a standard Mk II aftermarket barrel for comparison).

Attachment 106891

The top barrel is 7.5" from breech to muzzle, with 1" long reduced-diameter fluting at the muzzle end. It also has a through hole ahead of the chamber to allow it to be pinned to something.

Attachment 106888

This particular barrel has considerable annular scoring around the exterior of the thick part ahead of the chamber (odd given the hole for the barrel to be pinned!), which may or may not have obliterated some sort of stamped markings. Frankly it looks to me like something might have been there, but is unreadable now.

Attachment 106892

The short barrel is 5-1/8" from breech to muzzle, with 3/8" long fluting at the muzzle end. It has eight staggered rows of six venting holes each. I suspect this might have been a variant used in the long SOE/CISA can.

However, Peter's book has a drawing of a standard-length Mk II barrel with venting holes drilled along the rifling he states was for use with the SOE/CISA suppressor. The vent holes in the barrel below certainly straddle the rifling, and there is no evidence of interior burrs or sharp edges to the holes. This barrel also lacks the three annular "U" shaped recesses just ahead of the butt-end positioning collar as shown in Peter's drawing. It does not have any markings.

Attachment 106890

What think ye?

The top barrel is a barrel originally intended for a MkIII which has been salvaged for use as a MkII barrel by installing the re-in force barrel trunnion. These are quite common.

The middle barrel is "probably" for a commercial silencer. There were a number of international militarys which manufactured cans for Stens post WW2 - including the US as late as Vietnam.

The ww2 MkIIS and MkVI cans both had short barrels.

The hole in the re inforce is to install a split pin to capture the barrel to the MkII barrel nut. This "should be" a feature of all Mk2 barrels.

Middle one is not British and appears to be a modified Possibly French barrel judging by the chamfered chamber end.

The pin hole is to lock the bushing to the barrel rather than barrel nut. The bushing is a press fit and the cross pin stops the barrel being pushed out of it with the force of the bolt closing on a round. I believe these pins at some time were replaced with split pins which then also retained the barrel nut as a consequence.

---------- Post added at 10:25 PM ---------- Previous post was at 10:21 PM ----------

Oh and I can say the middle barrel wasn’t used on any British suppressor as they didn’t use the bushing and if I’m correct, that barrel will be made from solid and not the 2 part bush/barrels of the MkII/V

Quote:

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Originally Posted by tj214

This particular barrel has considerable annular scoring around the exterior of the thick part ahead of the chamber

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Those are simple rotational machining marks. It takes a bit of work to eliminate them and they weren't taking time. Not so unusual. The rest as stated, yes the vented barrel is for a can.

Thanks to all.

BP, I see your point about the pin to lock the bushing to the barrel, which I hadn't noticed before.

Was this present on only the Mk III barrels converted for Mk II use? I would think if you were making a new barrel, even during the war, it would make more sense to machine the entire unit from a single piece of metal. I note the short, perforated barrel in my collection does not have a pin or hole, and obviously the current aftermarket barrels are unitary. Due to the machined front sight lugs it appears a Mk III barrel could not be converted for Mk V use.

All production Sten barrels were of the same diameter stock, the Mk2 and Mk5 guns had the barrel bushes pinned in place. Machine time was the main cost in wartime and minimising waste. To machine a Mk2 or Mk5 bushing and barrel as one would take longer than separately. A good lathe could knock out lots of bushes in one pass, i.e. maybe 5 items at the same time.

I don’t personally believe Mk3 barrels were ever used as Mk5 barrels as I’ve never seen a Mk5 barrel with the short step breech end bushed. I would have to measure the bayonet lug end to see if it’s even possible. The Mk1 barrel appears to be identical to the Mk3 and it would make sense seeing as Lines simplified the Mk1 gun into the Mk3.

The standard Mk2 S guns used a shorter barrel which was more in keeping with the Mk1/3 style with reduced diameter shoulders at either end. If you see a Mk2 S suppressor unit breech end with the same fitting as the regular barrel nut then suspect it to be a replica. The correct unit has an extra section for the barrel to fit into.