Just a bit past that. It had to do with stitch welding in a bit of an arc, like tightening the lug bolts on a tire with a combination of slow cooling and peening.
Here is my favorite link. to the days before "heat 'n beat"!!!!
84 posted on 11/28/2003 11:00:20 AM PST by Eaker
(When the SHTF, I'll go down with a cross in one hand, and a Glock in the other.)