Just reread old Frank de Haas, "Single Shot Rifles and Actions", on the H&A falling block actions. He did not recommend them for any rifle conversion for several reasons: The receivers are made of cast iron. Though heat treated, any cast iron is of dubious strength. The barrels were not threaded into the receivers, but merely slipped in and held there by the single screw visible in the above photos between trigger guard and foreend wood. The firing pin, especially in the large shotgun action, is angled sharply upward. It's rear end is given an essentially downward blow to push it up against the primer, not the best mechanical arrangement for reliability and durability.
These H&A small medium and large actions were the cheapest true falling blocks ever made. So I would not trust it for anything other than blackpowder pressure loads in .38-55. .32-40 or perhaps 9.3x57R.360. Even the weak .45-70 factory loads may be too much because of the larger head diameter exerting more power against the breech. De Haas even mistrusted them for the Hornet.