Sten Mk2 Barrel Thread - Adaptor Required ?

Being a Sten owner and amateur machinist, I'll happily investigate a little for you.
However, I can't operate my lathe and mill for a while, as I've just had surgery to repair a broken right elbow!

My investigation shows the thread on the tip is M12 x 1mm pitch. The thread is about 7.5mm long on the tip, but the muzzle is threaded deeper than that (can't measure that until I get some assistance tomorrow).
That would give some leeway to make an adaptor for standard M14 x 1mm suppressor/tracer threads.

BTW: Did you think of hiding the tracer unit inside a MK IIS style full length suppressor?

Well done that man !

Yes, the idea is to have the tracer unit in/part of a mk2S silencer set up but I need some way of securing the tracer unit to the barrel to give it all some rigidity; I've already mocked-up the silencer, and have materials to hand to make a 'canvas' barrel shroud

Have been checking various web-sites but can't find a 12mm<>14mm male-to-male adaptor - is it 12mm CCW or CW, btw ?

Clockwise.

Have been checking various web-sites but can't find a 12mm<>14mm male-to-male adaptor - is it 12mm CCW or CW, btw ?

As Poacher said: CW.
It'd take me less than 1/2 hour to knock one up if I had use of my right arm. The tricky part is the 1mm pitch M12 - that's not a normal M12 pitch, but Apparently, brake pipe nuts come in M12 x 1mm, so you could confirm that way, and dies are available.
Other than that, it's a single-point threading job.

Have been trawling through looking for adaptors and there's nothing suitable that I could find; any 12mm fittings listed seem to be a different pitch and then they all seem to be metric to imperial converters.

Think that this could just be more trouble and cost than it's worth, tbh .........

When I'm able, I'll give it a try.

When I'm able, I'll give it a try.

As and when you can, it would be appreciated but please don't cause yourself any grief in doing so .........

If it does work out, maybe there's a market for Sten-compatible adaptors and some shekels to be made ?

If it does work out, maybe there's a market for Sten-compatible adaptors and some shekels to be made ?

I'll be in for a piece or 5 of those adaptors That is, if No1_sonuk wants to make those ofcourse.

I've made single-thread adaptors for Uzis, but I've never made double-threaded adaptors before. It'll be an interesting challenge to look forward to.

What converters did you look at? If I don't have to make the M12 thread, that would really speed things up, assuming there's enough metal on what's left to cut an M14 thread.

e.g an M12x1 male to M10x1 female adapter might have enough metal around the female thread end to cut a viable male M14x1 thread (thread depth 0.5mm).

For the mentioned AGM Sten. As you can hide the tracer unit inside a silencer, or have the tracer unit act as the silencer. And it would be all 'correct' for the looks.

Sorry, Arthur, I meant what pipe adaptors did Joker look at.
Some of the brake pipe adaptors might be suitable to modify - that would mean I'd not have to make the M12 x 1mm thread. I have the right tools to easily make M14 x1mm CW and CCW suppressor threads, but M12x1mm would take extra time, or I'd need to buy a die (male threading tool).

Sorry, Arthur, I meant what pipe adaptors did Joker look at.
Some of the brake pipe adaptors might be suitable to modify - that would mean I'd not have to make the M12 x 1mm thread. I have the right tools to easily make M14 x1mm CW and CCW suppressor threads, but M12x1mm would take extra time, or I'd need to buy a die (male threading tool).

Oops

Sorry, don't know anything regarding adaptors or the skills needed to make them

Sorry, Arthur, I meant what pipe adaptors did Joker look at.
Some of the brake pipe adaptors might be suitable to modify - that would mean I'd not have to make the M12 x 1mm thread. I have the right tools to easily make M14 x1mm CW and CCW suppressor threads, but M12x1mm would take extra time, or I'd need to buy a die (male threading tool).

Didn't save any websites but just searching via Google the only 12mm adaptors that I could find that had a pitch listed seemed to be either 1.5 or 1.25 .........

There are 14mm<>14mm adaptors for the MP5k but then the 14mm is the 'easy bit'.

We can't be the only bods who would like a Sten adaptor - if it's do-able it might be worth contacting Fire Support, Airsoft World, Action Hobbies, etc., maybe even Epic Mil. and asking if they're interested in taking a few ? Could be worth a few quid or maybe kit-swaps in lieu (cheaper for the suppliers) ??

What converters did you look at? If I don't have to make the M12 thread, that would really speed things up, assuming there's enough metal on what's left to cut an M14 thread.

This place has male to male 12x1 to 18x1.5, so depending on the hole through the centre there might be enough meat to cut the 14mm thread over the 18mm ?
No prices on there unfortunately
http://www.raceparts.co.uk/products/brake_and_clutch_hoses_fittings_and_adaptors.asp?section=Metric+to+Metric+Male+Male+Unequal+Concave

just looking at the problem differently,i assume once finished these are to look like silenced sten mk2's,if so then all this is un-necessary ,the tracer unit is to be fitted into a tube to look like the silencer,all that is needed is to fit it nice and true into the outer tube,this can be done by wrapping tape around the tracer unit at both ends until it slides nicely into the tube,then just cap the tube to stop the tracer unit falling out, obviously the end cap needs a hole in for the bb's.then you need a couple of round spacers that slip over the sten outer barrel and sleeve into the silencer tube ,these spacers will ensure a nice true fit of the silencer tracer assembly onto the barrel,the whole thing just needs to be secured in some way.just a thought ,obviously not such a well engineered solution but very doable .

Fitting it 'nice and true' is the tricky part .........

If anybody has one to hand to measure - what's the internal diameter of a tracer unit's 'inner barrel' (the part that the bb flys though) - how much clearance/tolerance is there for the tracer unit to be out of true ?

Another option could be to clamp the unit outside the barrel (a la Thompson's ?? ), although I think that the Thompson barrel is a fair bit wider than the Sten ?

Or to glue the plastic screw-in 'end cap' that came with the Sten (assumedly to paint orange if necessary) into an old Tracer end cap, thus giving the tracer unit a male 12mm thread; it would need to be fitted absolutely true though to avoid bb's possibly scraping the inside of the tracer unit and skewing out of the barrel, ref Q. above .........

My B&T tracer is 9-9.5mm internal bore so there is some wriggle room. Sticking the removable end cap of the ACM STEN to the back of the tracer would work but you wouldn't have an end cap for normal use (it doesn't look great without).

Owners of the VIVA STEN are stuffed - no threads at all. But how about this for a simple solution for both STEN types - a replacement outer barrel, simply threaded on the outside at both ends (dunno what the pitch of the gun end is though). That must be a doddle surely?

Owners of the VIVA STEN are stuffed - no threads at all. But how about this for a simple solution for both STEN types - a replacement outer barrel, simply threaded on the outside at both ends (dunno what the pitch of the gun end is though). That must be a doddle surely?

The length is a problem for drilling. I think it's a bit long for conventional drill bits to drill the bore from a solid bar.
If you can find a tube of about 8.5 to 11mm ID and roughly 16mm (might be 5/8 inch) OD, it'd certainly be doable. 8.5mm min bore for inner barrel, 11mm max to allow some meat to support an M14x1mm thread.
That'd probably be hard to find, though, so a correct OD tube with an insert at the muzzle end might be more practical.