Aardvark21045 has twice the strength of common mild steel (A36) and on top of that it’s heat treated to improve hardness. That is what enables this to be a breaching bar and a bit more than some holes drilled in bar stock.
Aardvark2You could try and I’m sure someone would buy it...but you would be more successful if you took 1045 carbon steel, machined it, ran it through a controlled heat treatment process, and then charged $30 for it. Stainless steel has a lower tensile strength than mild steel and a much lower tensil strength than 1045 carbon steel. Plus, you wouldn’t be able to heat treat Stainless steel to obtain the same hardness that can be obtained with 1045.