Buck Hamlin’s Lefever destructive testing, courtesy of Tom Archer
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=422672&page=2

Buck Hamlin was given an extremely well-used damascus barrel Lefever with a burst right barrel just past the forend tip. The barrel wall thickness at the rupture point was .010”, and the chamber was 2 5/8”.
With the intent to rupture the left barrel, Buck measured the bore diameter and started his effort with a box of 2 3/4” 1 5/8 oz. short magnums. After 25 shells the left barrel had no change in bore diameter. He then lengthened the chamber to 3”, and following 25 1 7/8 oz. magnums (lead #2 and BB) there was still no change in bore diameter.
Buck then lengthened the chamber to 3 1/2” and used 3 1/2” 2 1/4 oz. lead turkey loads. The left barrel blew after only a few shots. The wall thickness at the rupture point, which was almost aligned with the bursting point of the right side tube, also measured .010”.