I found this little thing rattling about in the bottom of the spares box the other day. Tony Williams has done an excellent write up all about them. See link below.
All inert, primer soaked in oil etc.
Dave.
http://www.quarry.nildram.co.uk/THV.htm
All inert, primer soaked in oil etc.
Dave.
http://www.quarry.nildram.co.uk/THV.htm