Building the Canadian Semi-Auto STEN

[Claven2]

Now here are some additional pics of the next build, as discussed above:

The ejector MIG welded in, along with plug welds for the barrel collar:


Here we see the welds cleaned up with a file:

Here is an inside view of the ejector:

Here the trigger plate tabs are just tack welded on, but the trigger plate collar has been welded across the bottom at the back of the tube, tacked at the corner joints and solidly welded at the top of the tube. Welding done with a MIG machine.

[NavyShooter]

Well,

3 test-fire sessions later, and I'm kinda frustrated.

Some folks might recall that I messed up my extractor slot a bit? My "new" extractor isn't working quite right, and though I'm getting the action to cycle properly now, I'm not ejecting the empties.

So, I'm at the point I think, where I need to mill the slot for the ejector a bit deeper, and lengthen the ejector a bit.

Will dabbing a bit of weld onto the end of the current ejector and filing/dremeling it down to shape work, or do you think I need to cut it out and put in a new one?

NS

[Claven2]

Some more progress on the new design. In this design, I lathed the center of an original selector button completely out, so that no matter what position it is in, it cannot act against the disconnector. Then I drilled a small hole in the remaining flange, big enough to hold a brad nail.

Next, I inserted the selector into the Sten, put in a section of steel rod cut from the above brad nail, and then MIG welded into the selector so that the pin cannot be removed. Now the selector can never be changed for an original un-modified selector and no matter the position, it will not press against the disconnector. This, coupled with the narrow disconnector slot, should go a long way to ensuring the gun remains a semi-auto, but the selector button still moves for nostalgic reasons

[Mick]

Here is a pic of my SA Sten.

Looks nicely finished Stan.

[Claven2]

Mick, the slot was cut narrow enough to keep the disconnector in position (in theory). If it doesn't function in practice, I'll put an unmodified selector into the gun and weld it permanently in semi position. The trick to the narrow slot is to prevent the trip lever from ever bypassing the sear bent on the bolt.

[tiriaq]

Flanges could also be added to both sides of the tripping lever to prevent it from ever shifting off to the side.

[Mick]

Mick, the slot was cut narrow enough to keep the disconnector in position (in theory). If it doesn't function in practice, I'll put an unmodified selector into the gun and weld it permanently in semi position. The trick to the narrow slot is to prevent the trip lever from ever bypassing the sear bent on the bolt.

The reason I mentioned it is that the selector switch slot gives additional support to the the trip lever and helps keep it in the right place. ( I know you already know that ) I thought about doing this mod myself but decided against it because of the above and also as I think it makes it easier to make full auto. I will not post the details here.

[tiriaq]

FWIW, the BD-3008 has its "selector" cut away, very much like the one shown in Claven2's photo. The BD selector is also free to move, but because of the cutout, this has no effect whatsoever on the disconnector.
Another option is to convert the selector into a safety. This can be done in a couple of ways. Claven2's first build had a disconnector confined to the central position, with a selector that either permitted foreward movement of the disconnector, or blocked it, to provide a safety position. A second method is to allow the disconnector to move to the left, but to have a block welded to the inside of the trigger box, so that when the disconnector is in the left position, it cannot move foreward at all.
Both of these safety conversions act essentially as trigger blocks; neither locks the sear.

[Claven2]

Flanges could also be added to both sides of the tripping lever to prevent it from ever shifting off to the side.

I was thinking of plug welding blocks to either side of the mechanism casing to limit side-to-side travel as well. Will probably plug weld from the back side to ensure a solid bond. Pics to follow... though I doubt the gun needs this to function reliably. The CFO might like it as an added limiting measure though.

[Claven2]

The reason I mentioned it is that the selector switch slot gives additional support to the the trip lever and helps keep it in the right place. ( I know you already know that ) I thought about doing this mod myself but decided against it because of the above and also as I think it makes it easier to make full auto. I will not post the details here.

No problem Mick, I think you are referring to someone welding material back onto the selector to make it function again, but you would also have to mill or file out the slot to allow transverse tripping lever travel. To my mind, this would entail significant modification - but I don't know how the CFO feels about it yet. I will probably do the welded-in block mod to compliment this setup and make it even harder to modify.