More Relumy stuff. This is sort of up elsewhere but may be of some use here. Firstly, some pics by Frakor from Danny's site http://forum.vintageairgunsgallery.c...m-air-pistols/
Now some findings from stripping the underlever and the break barrel.

From what I can gather, the 2 pistols share the same grip blank (but slightly different relief where the action goes + the Tempest break barrel does not have a hole on the underside for adjusting the trigger screw), trigger guard and Stock bolt/ grip screw, the trigger itself although the break barrel does not have the hairpin spring in the gap(Frakor's picture show one so maybe it should), having a spring under the sear instead AND the long cocking arm. The Tempest has a thicker and longer, short cocking link than the Hurricane.
The cylinders and pistons on the 2 guns are different diameters. On the Hurricane underlever pistol the cylinder diameter is roughly 26.5mm and the piston diameter 22.85mm. On the Tempest break barrel, the cylinder is 23.8mm diameter and the piston 20.5mm diameter. I've also found that the cylinder end pin on the Typhoon has a bigger diameter than the Hurricane. It is interesting that the Typhoon has a rivetted on piston washer instead of a special nut. Going off what ccdjgn has said, I guess that the break barrel came after the underlever and they used the grip blanks, stock bolts, trigger and trigger guard for cheapness. I'd guess that is why there is no spring guide as well and a single spring?. I find it odd that the diameters of the cylinders is different and wonder why?