Hi Gary,
The use of faux twist steel is up to you to decide if it is historically appropriate or not. It looks cool though.
The way I have heard it is done is by cutting long strips of cloth, twisting them, and soaking them in Clorox. Wrap around the barrel in a spiral pattern and leave it to etch the steel. Rub back with steel wool or similar. Clean thoroughly, then cold blue and rub back.
I have not done this personally, so take it for what it is worth. God Bless, Marc