I remember reading article in Sporting Gun about steel shot use in double shotguns. The English advise using steel shot in guns with heavier proof ie for 12br 1&1/4 tons 1&1/4oz or 2&3/4" chamber or equivalent of at least 1200bar. The shell case used should match chamber length. One must realize that at time that was written most loads were heavy waterfowl loads not upland or target style 70mm shells. Naturally brazed barrels are preferred to soft soldered ones. I would not hesitate using those shells in something like loosely or not choked Excel Arms Ugartechea because to me it would be like shooting steel cased non-copper metal jacketed .45ball ammo through Chinese or Filipino 1911.
