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Sten Disconnector


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#1 yohuang

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Posted 06 October 2019 - 09:58 AM

After 330+ days of waiting, finally I received my C&R STEN MKII (Long Branch 1945 made). I test fired 200 rounds, it worked fine except one issue -- It fires full-auto only no matter where I set that fire-mode selector. From the receiver opening, I feel the tip of that L-shaped disconnector being too low, and the bolt never touches the disconnector. I did not fully disassemble to take out the disconnector, but its exposed tip does not look being filed or worn... Was it out of factory like this??  No idea.

 

What should I do to fix this issue? Replace with another disconnector, or other solution? 

 

===

 

[Edit] I start like Sten. Initially, I bought it mainly because its price tag was not that shocking (still very expensive given its cheap appearance, but more affordable compare with almost all other MGs). After firing this in range, I started loving it, its fire rate is reasonable, and it's accurate. Most attractively, the whole gun along with 3 magazines can be stored in a small pistol case. My wife could not believe the size, and asked me to open the case to see "how could that be possible" :) It becomes my favorite. 


Edited by yohuang, 06 October 2019 - 10:14 AM.

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#2 huggytree

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Posted 06 October 2019 - 01:47 PM

Im not a sten expert but I do own one. I have fully dissembled and messed with mine a bit. Id recommend buying a parts kit or at least all the trigger group parts. Swap some parts and see what happens. I have a nasty looking sheet metal sear. Switching the sear with a milled one turned my gun into a 2-3 round burst gun. I swapped the parts back for now. The gun is known to have trigger group/sear issues. Over 100 manufacturers means things dont always fit together. I suspect swapping a few parts around might fix your problems without a gun smith

If the parts doesnt fix it Id just accept it vs spending $400 and 1 year of your life waiting for a gunsmith to fix it. Semi auto is only for someone new to get a feel for it. Not a function you will ever really use. Worth a quick do it yourself fix though

Post some pics of your new gun. Share it

Edited by huggytree, 06 October 2019 - 01:50 PM.

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#3 Black River Militaria CII

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Posted 06 October 2019 - 10:30 PM

>If the parts doesnt fix it Id just accept it vs spending $400 and 1 year of your life waiting for a gunsmith to fix it. Semi auto is only for someone new to get a feel for it. Not a function you will ever really use.<

That's comforting to hear, aside from being about the worst advice I have heard in years. And aside from the advice to "accept" a malfunctioning MG, if it wasn't for guys like me and the few others who graciously, patiently and with years of hard earned knowledge and experience who do the MG gun smithing for the multitude of incapable MG owners who insist on having their MGs function perfectly, you all would be s--t out of luck. You'll happily pay the exorbitant going rate to have a local mechanic plug in cookie cutter parts on your vehicle pulled from a box off a shelf after a digital diagnostic but you begrudge the MG gunsmith who has incredibly unique skills not taught in any school in the planet. I've done my share of vehicle wrenching for pay, BTW, so I certainly am not knocking them but they exist by the tens of thousands. Good MG smiths? Not hardly.
Damn, some people's kids!!!!
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#4 APEXgunparts

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Posted 07 October 2019 - 01:08 AM

After 330+ days of waiting, finally I received my C&R STEN MKII (Long Branch 1945 made). I test fired 200 rounds, it worked fine except one issue -- It fires full-auto only no matter where I set that fire-mode selector. From the receiver opening, I feel the tip of that L-shaped disconnector being too low, and the bolt never touches the disconnector. I did not fully disassemble to take out the disconnector, but its exposed tip does not look being filed or worn... Was it out of factory like this??  No idea.

 

What should I do to fix this issue? Replace with another disconnector, or other solution? 

 

===

 

[Edit] I start like Sten. Initially, I bought it mainly because its price tag was not that shocking (still very expensive given its cheap appearance, but more affordable compare with almost all other MGs). After firing this in range, I started loving it, its fire rate is reasonable, and it's accurate. Most attractively, the whole gun along with 3 magazines can be stored in a small pistol case. My wife could not believe the size, and asked me to open the case to see "how could that be possible" :) It becomes my favorite. 

 

My MKII STEN arrived with the exact same issue.
Previous owner said he noticed that the push button didn't do anything and he never looked into it.
I fitted a different "tripping lever" to the gun and noted the one I removed had the tip filed down.
I found out why, the bolt would catch the lever.
So I shaped the tip, shortened it a bit and that seemed to get everything working properly.
Then I switched over to the normal bolt (the previous owner only ran the lightened bolt and so that is where I started)
That is when I discovered that some STEN bolts have a nicely tapered angle on the underside of the bolt face (facing rearward)
Others have a square cut, and that catches the tripping lever and drags the bolt speed down.
I modified my bolt (made the angle) to work with my tripping lever and now both bolts run "full auto" and work as open bolt semi-auto's.
I can see why the British and Canadians have school trained "Weapons tech's" to support their fielded firearms as repairs are not as simple as swapping parts.

Richard


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#5 DINK

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Posted 07 October 2019 - 06:03 AM

If your Sten came out of CT, that's probably why the semi-auto doesn't work.  Due to our idiot legislators, we can have machine guns in this stupid state, but not if they're "select-fire".  The easiest way to remove the selectability from a Sten without major surgery is to shorten the tip of the disconnector and I have done several of these conversions myself in order to make them legal here.  Just swap out an unaltered one and you will be back in business.


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#6 peter kohler

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Posted 07 October 2019 - 08:21 AM

the disconnector has been filed down or jus worn off  .  that's why its not tripping the semi auto.    been there done that.   another thing you can do is pull the fcg cover off and look see if the bolt is tripping it when in the semi auto position.     the trip lever should be in the center position    


Edited by peter kohler, 07 October 2019 - 08:27 AM.

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#7 huggytree

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Posted 07 October 2019 - 04:29 PM

shooting a full auto in semi is like hiring a prostitute and holding hands

 

if you cant get it working skip it. ill bet you get it going though

 

smiths are 1 year+ out these days and not all of them fix the problems correctly.


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#8 StrangeRanger

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Posted 08 October 2019 - 09:25 AM

Not all competent FA gunsmiths are "1 year+ out."  It depends on the smith and on the magnitude of the job.  If he shops around for a simple one-day repair like this he can find one who would do the job for less than $400 and way less than a year.

 

I'll defer to your expertise on prostitutes


Edited by StrangeRanger, 08 October 2019 - 09:26 AM.

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#9 johnsonlmg41

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Posted 08 October 2019 - 07:57 PM

Not all competent FA gunsmiths are "1 year+ out."  It depends on the smith and on the magnitude of the job.  If he shops around for a simple one-day repair like this he can find one who would do the job for less than $400 and way less than a year.

 

I'll defer to your expertise on prostitutes

Indeed  I'd agree

 

  A rather well know smith did a major project on a gun for a buddy of mine and turn around was about 2 weeks.  Like anything, repeat and good customers garner first priority.  If you are "Joe

Blow" you get "maybe a year" for an answer.  Its possible Joe Blow does better with the hookers though?

 

On the rare occasion we send something out, it's never that long, other than some custom "one off" rare parts we've had done, but those were sent to highly skilled folks who only take work from a small client list.   If you're sending stuff to the guy nicknamed  "slow Dave" you should know he has others that send him a lot of work and that takes precedence, just like any other business owner that caters to those that provide steady business.  

 

We had an uber rare 100 yr. old scope missing a base, and that got made in 2 days on a wire EDM overnight while no one was there.  My guy programmed it in at the end of the day, left the shop, pulled it out of the hopper the next morning, and got it to me the next day after work.  Only one of these guys has a web presence, but I only call or stop in.  As they say it's "who you know".


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#10 maxfaxdude

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Posted 08 October 2019 - 10:58 PM

Replace the disconnector with a slightly longer disconnector as others have said.  Your disconnector may be worn and may have been ground off.   If I'm not mistaken, the disconnector trip should be about 26 mm tall. 


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#11 2ndArmored

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Posted 10 October 2019 - 07:33 AM

I had the same problem (initially) with mine.  I'd get occasional bursts on semi-auto.  It turns out the finger on the disconnector was too short.  My uncle (a machinist who lives for guns and classic cars) grabbed the disconnector, put some weld on top, re-machined the now-taller contour, and it's run like a champ ever since.  I paid him in cigars when his wife wasn't around (although I'm sure she knew...)

 

These parts are 70+ years old and made in a hurry by myriad companies.  So a bit of fine-tuning is sometimes needed.  That process can be an adventure or a pain in the a$$, but don't settle for something that works most of the time.


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#12 yohuang

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Posted 11 October 2019 - 10:24 PM

Sorry, so busy these days.. finally got some time today, I fully disassembled the triggering system. Since I have never disassembled STEN trigger before, I took a picture before I remove those pins. Here is the before disassembly picture:

 

Attached File  before.jpg   147.71K   11 downloads

 

Disassembly was easier than I thought.. When I tried to put everything back, I met a problem: I cannot remember the orientation of that small spring on the sear.. I used that "before assembly" picture showing above as a guide, and found it's not easy to put things back...

 

This forced me to search the Internet to find STEN trigger pictures... The most useful was found being a year-2011 post on a cut-away STEN:

 

http://www.machinegu...showtopic=13410

 

Looking at the cut-away gun's picture, "Wait a minute, my STEN was assembled wrongly by one of the previous owners"...  Please note the long arm of that small sear spring sitting under the L-shaped lever on the cut-away illustration. And it was obviously sitting above the L-shaped lever in my "before-assembly" picture (so that  long sear spring arm was invisible from the bottom view in the "before-assembly" picture).

 

So, I re-arranged the sear spring orientation. Re-assembly became much easier. And, surprise!  The gun could do semi-auto now (via manual operation, I will test in range over the long weekend).

 

here is the "After-reassembly" picture of mine:

 

Attached File  after.jpg   146.56K   13 downloads


Edited by yohuang, 11 October 2019 - 10:28 PM.

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#13 DINK

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Posted 12 October 2019 - 05:43 AM

Good job!


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#14 yohuang

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Posted 13 October 2019 - 08:54 AM

Re-tested in range -- everything works as expected now. To save wearing on parts, I bought a spare barrel and a spare bolt (at the bottom of the picture), they work well too. Everything still fit into the pistol case.

 

Attached File  cased.jpg   194.92K   3 downloads

 

 

 

 


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#15 2ndArmored

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Posted 13 October 2019 - 10:05 PM

To quote my old high school auto shop teacher, "Well there's yer problem, son."

 

Glad you got it worked out (and learned a memorable lesson on the gun's function!)


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#16 yohuang

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Posted 14 October 2019 - 06:56 AM

Shooting this STEN, now the task becomes testing those magazines. I got a dozen or so magazines, most work well, but there are three of them are faulty. With those three magazines, the gun just  behaved like the one in the movie on "assassination of Heydrich" (I forgot the exact name of the movie) -- the bolt went forward, chambered a round, but no bang. There was a small shallow dent on the primer, not deep enough to fire the round out. I dumped those three faulty magazines away. With good magazines, this gun performs well.


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#17 StrangeRanger

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Posted 14 October 2019 - 07:13 AM

Many, many films on the assassination of Heydrich.  Operation: Daybreak is probably the best known, if not the most accurate, in the US.  I haven't seen any of the several Czech films but I'd wager they tend to be a bit more historically correct.


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