The short answer is no, there is nothing "normal" about 70 hours gunsmithing time on a double rifle.

It just depends on what was done. A complete restock, correctly done, can burn through 40 hours. If the action and fore-end need re-color hardening and barrels and furniture re-blacking, with lots of corrosion issues to deal with and engraving that needs to be picked up...yeah, that could take another 30 hours. Absent something like a re-stock to soak up a lot of hours, it sounds like this gun was a real mutt.

I doubt re-fitting the fore-end wood had anything to do with it. When a second set of barrels is added to be used with the same fore-end, matching the profile of the original barrels is the only way. I'm sure that was done in Ferlach.

Some "dogs" can be correctly repaired and be fine. Some can't. Talk to Mazur to see what was done. Then get the gun and the invoice to a gunmaker like J. J. for a hard look.
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