Starting a STEN Mk V SBR in the US

[17thairborne]

Decided that the Dremmel tool was not such a difficult Beast to overcome and put it to work yesterday. I have made all of the cuts except the straight cuts for the charging handle and the trigger mechanism at the bottom of the tube. I will do those today. As you can see my Dremmel work is only fair at this point, but no damage done. I should ensure I drill a hole at every corner though. It makes connecting the dots easier. Here is one of the two slots at the rear of the tube.




And the nearly completed tube partially inserted into the Rear head Casing just because i have to see what she's gonna look like!!!



You will notice that i did not follow the template on the spent round discharge port. I used the torched tube and took measurement from it to mirror it's configuration. Upon studying the Mk II and Vs in Peter's book, every image taken of the right side shows the tube opening shorter than that of the Magazine Housing. I wanted it to look right.

I'm not sure if IO did this because of differences in how their bolt slings spent casings out, but I think the physics would be the same? Peter can you analyze?

1. Same cartridges in original 9mm round causing 'blow back" pressure to move the bolt back,provided it is not a hot load, should be the same.
2. Spent case striking the ejector bar at the same position as on the original STEN
3. Same extractor pawl and spring providing similar throwing moment as on original STEN


All of this should cause the same force to sling the casing out of the chamber at the same angle. I only consider that the different spring tension and weight of the Breech Block (Bolt) might make a difference, but it seems the tension of the extractor on the rim of the spent cartridge and the point at which the back of the case strikes the ejector would be what determines the angle of ejection, not the speed at which the bolt moves to the rear. What do you think?

[17thairborne]

Finished all of the milling and drilling of the tube. All that remains to finish the tube is the filing. I have quite a few rough areas to refine. especially the access hole for the trigger parts. I've added a photo to illustrate the method in which I milled the discharge port in the tube. Once I finish refining the edges it will match as close to the original profile as possible. I also drilled three 3/16 inch holes in the forward part of the tube. Those will be weld filled to mate the barrel retention nut with the receiver tube. I will drill three similar holes through the rear head casing so that the rear portion of the tube can be welded to the trigger housing and casing. Final holes will be 2 in each of the trigger housing tabs to secure the trigger housing to the tube. Here is the working mock up with the furniture, tube, housing, barrel nut/shroud and the magazine housing in place. I need to buy another screw and washer for the pistol grip.

[Peter Laidler]

The screw for the pistol grip(s) is a British thread - I forget which off the top of my head, that you might have a problem sourcing over there.

Can I suggest that when you've finished and tested the casing that you send it together with the other bits like the trigger, butt bracket, sling and bracket, barrel nut and barrel etc etc to Brian at BDL Ltd in SC who will phosphate it and paint it in the correct paint.

Re the questions above, it's worth bearing in mind that the Sten gun was designed to work on the particularly hot UK/Commonwealth Mk2z 9mm ammo so extraction/ejection isn't a problem. Also, remember that extraction per-se isn't performed by the extractor in a Sten/Sterling gun. The fired case acts as a piston and is 'blown' or pushed backwards as opposed to being 'pulled' backwards. The extractor only comes into its own when the left side of the case strikes the ejector and then, the extractor acts as a simple fulcrum to direct and tip the case out. Obviously, the extractor can 'pull' a round out, but in theory, it would only ever be used to pull out an unfired round or a drill round. Hope this has answered the Q.

The Sterling extractors were all finished by hand to create a small radius on the................... Ooops, sorry.....,, going off at an irrelevant tangent here

On the basis that you are re-watting a Sten to SBR spec, is there any reason why you couldn't do the same to a Lanchester?

[gsimmons]

Yes, Peter you could re-activate a Lanchester as long as it meets ATF standards. What a great project that would be.

[17thairborne]

Peter,

First of all, thanks for the clarification on the ejector/extractor. Based on what you say, I should not have any issues with the shortened size (same as original Mk V) of the ejection port on the tube. You are bolstering my confidence to proceed. I appreciate this as I have never built a weapon before.

Parts are actually quite available here in the US. There are two sources that I have been hawking. Most of the small bits are available there.

STEN SPARE PARTS - STEN GUN PARTS | AA-OK and APEX Gun Parts

As for the finish, my intent is to purchase materials for the dark-grey phosphate finish with that and an available product that matches the original armorer's black. When everything is refined, welded and manually tested for fit and function I will blast all of the components using a fine media so as not to pit the surfaces, then I will finish with the phosphate and paint. Cost is a concern for me, so I am doing all the work in house. BDL has some nice British arms on their site!

Have not even thought about the Lanchester! Was thinking about the Mk VI last night.

I will post a picture later ofthe ejector that I salvaged from my old tube. Will have some questions about that also.

[Peter Laidler]

The Mk6 will be a bit more difficult because the Mk6 incorporates as Mk2 foresight blade and the dovetail has to be machined across the top of the barrel seating bush and casing.

We used a Mk6 Sten/L34 and a DeLisle on our ranges several years ago and a rudimentary noise/sound Db meter so the tests weren't scientific but were positioned the same for all three. To be honest, against the Mk6 Sten and the little L43 Sterling, the DeLisle was audibly noisier, it was crap! I told Prof Dater the findings and he agreed!

As a matter of interest, if you had a dummy silencer, a sort of empty tube on the end of a SBR Sten, would that count or be frowned upon by the alphabet men/BATF?

[Brit plumber]

I had it brought back together with a few new PKM's but just kept the Mk1/1 specific stuff. If I knew you then, you could have had it BP...., do dewat of course.

That's the story of my life Peter....always too late! But thanks for the thought. If you ever come across someone wanting to dispose of a Mk1 you know where I am.

[17thairborne]

The Mk6 will be a bit more difficult because the Mk6 incorporates as Mk2 foresight blade and the dovetail has to be machined across the top of the barrel seating bush and casing.

We used a Mk6 Sten/L34 and a DeLisle on our ranges several years ago and a rudimentary noise/sound Db meter so the tests weren't scientific but were positioned the same for all three. To be honest, against the Mk6 Sten and the little L43 Sterling, the DeLisle was audibly noisier, it was crap! I told Prof Dater the findings and he agreed!

As a matter of interest, if you had a dummy silencer, a sort of empty tube on the end of a SBR Sten, would that count or be frowned upon by the alphabet men/BATF?

It would be much more of a challenge for sure. It seems there are lots of parts to fabricate. It looks like the barrel is completely different also. If the tube was empty, with no sound reducing components I suppose it would simply be considered a large flash hider!!!

I suspect you could do that much easier by using one of the 16" barrels and making a tube/shroud that looks like the MK VI. That would be legal as long as the length was not less than 16", then you'd have to file for another SBR. I'm not quite sure if you need a separate Form 1 for the suppressor and yet another to go with the special barrel for it, even though I have approval for an SBR. I suppose the SBR Form 1 goes with the receiver, not the barrel, so technically all I would have to do would be submit an ATF Form 1 for the suppressor. I'll have to call first.

DOes anyone have any info on plans for the MK VI suppressor guts? The 30 individual baffles might be relatively easy to make if they were done in two components, a disk with hole fitted to a collar of the inside diameter of the tube.

[Peter Laidler]

The drawing is in the book I seem to recall. Better make a small press tool to punch out baffles

[browningautorifle]

The 30 individual baffles might be relatively easy to make if they were done in two components, a disk with hole fitted to a collar of the inside diameter of the tube.

Examine frost plugs for an engine block. Almost correct and just need shape and hole...you can choose the outside diameter so they just fit...