Many thanks for the info.
The lettering is as follows: 100.91(2) 92 long.93 then an anchor symbol and a bomb symbol then it continues with R.4.L 98 then m in a circle. On the percussion cap it has got SFM 1138 and underneath a small bomb symbol then 1238. On the outer edge is a P and what looks like a fish hook !.Hope all this helps. Many thanks for your time sorry I couldn't get another pic on, for some reason it wouldn't work.