Ed, for you and surely others that may have a problem identifying the differences between Extruded and Stamped Sheetmetal magazines, I put together this collage of photo illustrations that may be helpful. There are early H-S extruded police mags that have a rear pinned mag bottom, but most extruded mags are the center-pinned type.
MOST extruded mags are cut at 90 degrees to the back at the bottom edge which causes a small portion of the front half of the shell to be exposed when inserted into the gun...
The stamped mags are GENERALLY cut at an angle that matches the bottom of the gun so none of the mag tube is exposed when inserted in the gun.
Newer reproduction mags (like Mec-Gar) use a one piece sheet metal tube that is formed and shaped to the proper dimensions so they won't have the crimp, but they are not exactly "extruded" like the original mags that were formed out of hot steel pushed through a die and then machined to size... The triple-K variety mags are typically two halves (front and back that are spot welded together...