Went and dug out my Brno literature and found 1986 Progotrade pamphlet for BRNO Super Express, barrels are dovetail joined at chambers and barrels soldered there length with a rib.
Kersten-type breach cross bolt
Coil spring sidekicks mounted on the inside of side plates.
Selective automatic ejectors.
Etched side plates.
Integral dovetail for scopemounts, and factory aligned front sight and folding rear sight.
Dense European walnut stock with hand cut checkering.
Rubber recoil pad.
The BRNO Super Express are equipped double adj. Set triggers.
BRNO Super Express 375 H& H O/U barrels are 600mm/23-1/2".
Overall length 1020mm/40".
Selective Ejectors.
Factory offers 6 grades of elaborate hand engraving.
If this sight was smart I could post pictures of pamphlet from phone, SORRY!
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Last time I saw one come up for sale was a few years ago here in 458WM, $3500 with minimal engraving, and that was a giveaway price!
Hope this helps
Dale Z
"Kersten-type breach cross bolt".... absolutely BUT remarkable in that is just the locking system that is integral (and formed with) the top barrel. The bottom barrel has been formed with its own integral locking system consisting of "two large integral lugs" that are ALSO engaged when the action is locked up. .... combined with the fact that the two barrels are dovetailed together.... (another reason why it doesnt need to rely on the strength of the soldered side strips) ... makes it is a VERY strong action.