The eagle on the right is the police acceptance marking
And anyone can shoot their guns, but yes, breachblocks do get damaged and so if willing to risk or can afford it; then you can risk a $3000+ dollar gun losing more than half its value.
I have no idea what a Horma golf club is but I am assuming it is not 70 years old?
Are they still made?
As they say, go ahead, shoot it, makes my 1939 police have more value at every shot