A friend of mine recently acquired an HK SP89. According to the previous owner, the gun had a full stretch conversion done by Fleming. Everything looks correct except it is missing the antler proof mark next to the date code. For comparison my friend also has an original SP89 still in the box and it very clearly has the marking. The SP89 in question has a "KD" date code indicating it was made in 1993. Does anyone know why this proof mark might not be there? Is it possible that it was covered when the gun was refinished? I am trying to find out as much as possible about these pistols and any input would be appreciated.