Bad things happen to barrels since leaving the Heuse-Riga shop Lloyd, and we have an obligation to do what we can to establish barrel integrity (starting with wall thickness) but the makers said the barrels were for Nitro powder
1895
And in 1907 Sears said they were safe with Nitro powder
"Every gun we offer for sale...is made to stand any proper load of nitro or black powder..."
Remember, pre-WWI 1 1/4 oz. 3 1/2 Dr. Eq. Bulk and Dense powder shells generated pressures above the SAAMI 2 3/4" 12g maximum of 11,500 psi
