Robert,
Don't know what you paid so can't comment on that side although you mention a £100 is this what you could loose if you return it ?, it may be worth contacting Simon to see if the serial number on the wrist matches one on the list of L39's , other option if your not too happy contact the seller and arrange to return it.........
I,ve bought and returned a few lemons in my time so know what its like...... a few examples are on this thread Buy the rifle not the story!!!!! post #59