As a Gunsmith who does jug chokes, there are several variables in doing twist steel. As mentioned, wall thickness is important. Also consideration is given to overall condition of the bore. Pitting, rust, grain quality ,all effect structural integrity. Jug choking has become popular with turkey hunters in hope of range improvement. It is not an end all for everyone. Unlike screw chokes, they still require some work on the part of the shooter to develop a load to maximize expected goals.