I can tell you the chemical composition for several foreign steels
Krupp Special - C-0,61% Mn-0,65% Si-0,434%
Boler Antinit - C-0,117% Mn-0,49% Si-0.299 Ni-8,51%
Poldi Anticoro - C-0,145% Mn-0,50% Si-0,45% Ni-7,78%
As you can see barrel steels are very mild steels with very low carbon content. All ordinary not antirust steels are about the same in chemical composition.
The best rods for barrel TIG welding would be very very mild steel rods. The shield gas is a must. Otherwise melt steel eats oxygen and becomes porous.
