Starting a STEN Mk V SBR in the US

[17thairborne]

Plumber,
Thanks for the insight. here are images of my new tube, just received in the mail There is no slot for the pin on the back side. What you say makes sense, if the pin was already installed for the sight as it is on my head casing, I will need to mill a small slot at the 12 0'clock position to accommodate the pin which will correctly position the tube in the head casing. Does that sound correct? Will confirm with you before beginning.








Last image showing the end milling to accept the barrel seating.

[Peter Laidler]

I was asked to arbitrate in the UK over a person who wanted to strip a dewat Mk2 Sten in order to make it into a similar Mk5 Sten that also had to remain dewat!!!!! In fact he already had done the deed and there was some question as to whether he had RE-watted the Mk2 before he DEwatted it to make the Mk5. No...., I didn't understand it either really! Anyway, he'd pretty well done what you have done but kept the dewat breech block and barrel.

To be honest, they were jumping up[ and down like frogs on fire because he had made a Mk5 type barrel from solid and kept the original welded up/split Mk2 barrel. They took my honest opinion that it was still a dewat Sten but he had put a hardtop on his MGB version and made it into an MGB GT!

I let the cops fire both types on the range and they were happy. In fact, they were so happy, their pals came up the following week!

Great project 17th. Wish we could do it here........

[17thairborne]

Peter,
Great story. We have several similar stories in the colonies where either overzealous builders or overzealous cops get into the act. Makes for great observation sport. Sounds like you kept a situation in order. As long as we do the paperwork and follow the rules, all is fine. I am fortunate to live in one of the few conservatives areas of New Mexico where the Law Enforcement folks understand the reason for a well armed citizenry!

you know....there's nothing stopping you from getting on the Mayflower II and slipping out from under the king's (read queen's) icy grip and coming to our fine colony, where you can be supplanted under the icy grip of another form of controlling government!

[17thairborne]

Also the V changed to a 5 in Oct 1944 I think it was.

Did not know that. Thought it was some time in 45

[17thairborne]

I spent more than an hour studying the new tube and comparing notes from other builds and I have noticed a significant difference between the IO tube and the original Mk V tube. The ejection port for spent casings is very different between the two. The original tube has a port that is tapered smaller towards the front of the tube by 1/18 of an inch. The IO post is also 3/8" longer than the original length of 1 7/8". I will call Jason and ask why he drew the template in that manner.

My plan is to mill the port as close to the specs of the original tube as possible. Does anyone see any problems with doing that?

[17thairborne]

Just spoke with Jason, and he does not see any issues with following the original specs for the tapered port and the difference in length. I will mill it to more closely follow the original size and shape.

[17thairborne]

Set up the drill press for milling today. i mounted my x/y axis table and ran some test milling on the old tube.

CAUTION..............I realize that one should not use a drill press as a mill because of the potential for the side loads to cause the chuck to fly off and it could ruin the bearings. I will use the drill press and make plunging cuts along the vertical axis of the chuck and minimize the side loads. I will not use the hand wheels to "feed" the material on the x/y axis while the mill bit is in contact with the metal, I will simply use them to make small precise movements along one axis while the bit is up and continue to take small vertical bites out of the metal and create a straight cut. The test cut on the old tube worked fine.

I used the formula for computing rmp, based on the hardness scale for 4130 steel and the feed recommendations 4 x sfm divided by mill bit diameter. I set the drill speed to the closest setting. The best I could find was that 4130 has a hardness of about 385. the recommended sfm is 35, so for a 3/16 bit I should set 560 rpm.

PS: I suck with a Dremmel and cut off wheel.





I decided to scavenge the Barrel Seating (barrel nit) from the old tube. I milled out the places where the nut was welded to the tube. I tried not to plunge below the thickness of the tube. I then cut the tube near the hole for the barrel nut hole as shown on the red line in the photo. This way i could cut completely through the tube at that location and pry it away going slowly where the welds were. I used a dremmel to clear these spots before prying the tube piece away.

[Brit plumber]

Mill the port to the spec of the original tube and then fit the mag housing, it will show if there's any area that protrudes into the mag well ejection port. If it does you can live with it or file the tube to match the mag well ejection port (Even if it looks skew). I've seen quite a few where it appears either damage has been blended out or someone has adjusted (Filed) the port because the cases were getting trapped. Peter will know if that was permissible or if not, if it happened regardless.

---------- Post added at 08:30 PM ---------- Previous post was at 08:27 PM ----------

Are they welds or rivets? I can't remember on the mk5 but the mk2 are rivets.

[17thairborne]

Brit Plumber,

Okay...thanks for the guidance. On my kit gun, the ports on both the tube and the magazine housing were made with that taper to the front (smaller front than rear) I will do the same with my build. They both seemed to match up pretty well. I'll try to do the same.

If they were rivets, they were filed flush to the contour of the tube. It seems like the diameter of the top is larger than that which shows in the inside of the nut. They look like pins to me from the inside, but then with the larger upper diameter i guess flat head rivet might be correct.. I am thinking about drilling three holes into the end of the outer tube only, inserting the barrel nut and then fill welding the 3 holes and filing round again. What do you think?

[17thairborne]

I received my deluxe copy of Peter Laidler's book on the STEN. I stayed up late last night digging through the pages. Very fascinating both from the perspective of a collector and a historian. I am finding out many details about the STEN, and am learning a lot about the various markings on the gun and magazines.

Two magazine that I purchased recently have marks in particular that were highlighted in Peter's book:
1. 66 on the magazine Base Plate: Lee and Beilin Ltd of Wembley
2. Diamond with letters inside: Fred Lievbentruth Ltd

I highly recommend every STEN builder get his book "The STEN Machine Carbine"

I just updated Amazon with a rating!

GOing back to read again before doing some milling!