The twist barrels are marked with H.R.F.; the mark of Heuse-Riga Fils.
Jon's point is that the original chambers were 2 9/16" and if now longer, the end of the chamber wall thickness may not be adequate.
Regarding safety & load recommendations, please see
https://docs.google.com/document/d/1ZIo0y746UsSRZIgRuuxwAbZjSBHitO_EanvwLYc-kGA/edit
If you purchase the gun, set up a visit to a double gun smith within the 3 day return for an evaluation, esp. wall thickness.

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