Sten SOE/CISA Silencer Ratchet Plate Details

[tj214]

Just now received a "case resolved" email from the MOD system and the actual respondent organization that did all this exceptionally fine work is listed as "Courses - Tech School, Marlborough Hall." One wonders whether a volunteer at that organization took all the time required for this as typically a solder or government civilian would have far more important work. In any case, I'm amazed and very thankful they went to all this trouble for such an esoteric request.

Now to see what I can do with it...

Information

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[Brit plumber]

I think Marlborough Hall is part of the Defence Academy at Shrivenham. I wasn’t aware they had a firearms collection but good to know. I would like to know what else they hold.

[tj214]

Possibly limited interest because it's a replica, but I gave myself a Christmas present. Bit the bullet and fabricated the ratchet plate assembly to fit on the replica CISA tube I fabricated last year.

I'm pretty pleased with the results. The project is about 98% cosmetically accurate, although as noted above, my version of the CISA tube contains a legal (tax stamped) B&T 9mm can embedded in the tube rather than the original baffles assemblies. I could have manufactured all the baffles, etc., like the original, but am too lazy to do all that work. What I've done here was plenty of work as it is!

This is the original as photographed in the British Army armament museum:

Attachment 114126

Attachment 114127

This is my version. Although I have the US tax stamp for the B&T suppressor, it has a normal Sten Mk II barrel and so far I haven't felt like paying an additional tax to make this a SBR (short barrel rifle); hence the paratroop grip rather than T-stock.

Attachment 114128

Attachment 114129

I made the T-handle tool to unscrew the B&T can from inside the CISA tube. The long rod is 0.34375" tool steel drill rod to use as a bore alignment rod, which you know is absolutely critical if you've ever used a can.

Nobody sells one long enough to use in a 22.5" can, so I had to figure out something else. Drill rod worked perfectly. 9mm converts to 0.35433, but the barrel lands demand a slightly smaller diameter. My experiments show 0.34375 works perfectly with my aftermarket standard Sten Mk II barrel.

Attachment 114130

Attachment 114131

These are the ratchet parts I fabricated based on my study of the MOD pics (published above). MOD did not provide dimensions, so I took measurements on my Sten receiver and used a lot of LAR analysis (Looks About Right...). Guess I was fairly accurate as everything fits same as the originals. I'm not going to overload the forum with the engineering drawings I made up, but feel free to PM me and I'll send them to you.

Attachment 114132

Attachment 114133

Glad I did this, but I’ll never do it again. Luckily I have a good friend who let me use his fully equipped machine shop so fabrication was not a huge deal. For comparison I sent my drawings out for quote, but don’t ask me how much the commercial shops wanted to charge—I’ll start crying again.

What? Oh. Sorry. They're calling me back to the looney bin--gotta go now.

[browningautorifle]

Looks good too.

[tj214]

Thanks!

[Peter Laidler]

Yes, Marlborough Hall houses the MoD scientific or technical collection. Warminster hold the USER technical collection