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?