I would
love to see a photograph of a registered tube that shows the Sterling cuts. Not sure if parts kits for Sterlings were even around in 1986, otherwise why register a tube for a gun that could not be made? According to the Guns of Dagenham book, the Mk.4 was phased out in 1994.
My Sterling was made by Andrewski in 2000 on a BARR Armsmaker registered tube. This was soon after he got permission from BATFE to modify a registered STEN tube to work with a Sterling parts kit. After seeing the Small Arms Review article on it I knew what 9mm smg to get. I had tried all the affordable 9's (i.e. not a MP 5
). Tried the MP40, Stens, UZIs, MACs, Smith 76, and the Walther. They all were functionable but had things I did not like such as wobbly stocks, bitch to load magazines, parts availability, sub-optimal ergonomics, etc.
It originally had the original larger slots of the STEN. I later was invited to send it back to Andrewski and it was modified (after another round of permissions from the BATFE masters) to the correct dimensions of the Sterling. It runs like a top, is accurate, the stock locks up solidly, and the magazines load like butter. Bought the spare parts like a barrel, bolt with recoil spring, grip assy, and a trigger group when they were still inexpensive.
The only downside is the difficulty in mounting a suppressor. Been thinking of having an extension made for the spare barrel.