I do not know who is the current US-market importer. Brno (Czech Republic) manufactures the ZH300 series over/under guns. I have owned two earlier versions -- differences between 200 and 300 series appears to be cosmetic.
These guns are stone axes -- impossible to break or wear out. No cocking rods, Kersten double bolts and under lugs. Double triggers, front is single nonselective, rear is bottom only. Mine are machined steel from bar stock. I am uncertain they are still made that way, but I suspect YES.
All parts interchange without fitting. ALL PARTS!!! Fewer parts than any other double gun, except, perhaps, the Darne "V" model or its offspring by Fusil Paul Bruchet.
Single set trigger is available. Safety functions like M1 Garand. The last time I checked, ZH 3xx had available 27 sets of barrels, some of which are combo, some double rifle, some shotgun.
They used to be under $750 for shotgun/shotgun. Dunno current pricing.
Oh, did I forget to mention Brno Q-D telescopic sight mounts?
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Things I do not find unacceptable, but some people might: extractors only; profile is not smooth and sleek. This is forced by its unusual break-open mechanism. And the break-open is more acute than over/unders with cocking rods.
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This over/under is the best thing since sliced white bread.