in reading the OP's description again, i focused on the term "one of the awled holes will tear when the stitching is pulled tight". i think that is the key - along with the thickness of the leather. the "bearing surface" , if you will, of the thread is extremely small. and if pulled tight enough, it will rip out any hole. or, in the case of a punched hole, will rip into the leather regardless if it is round or not.