Sir,
if the loading gate swings forward rather than down, it is Danish.
The M89 also means Danish.
The barrel is covered with a tubular shroud, so the barrel is not really that thick--unless rebarreled!
And should you find a reliable source of 8X58DR cartridges that do not cost an arm and a leg, I do so wish to know the source!
I have three [3] of the things myself.
Thanks and good luck, Paul
Houston, Texas