[lugerholsterrepair]

Pretty simple actually. The rolled steel crimp mags are like a can of beans. The metal seam is joined by hooking the metal edges together in U shape and squashing them together to attach them.
The extruded type have no seam at all. They are pushed out of a die whole in circumfrence so no seam is needed to join an edge cause there ain't no edge to join.

in Norm's excellent photo's you can see the seam below the spring about a quarter inch below the spring window.
On the extruded mag you can see a line there but no seam as it is whole metal that does not need to be joined.
You will also notice differences in the steel of each mag. The top sheet steel mag looks more like the bean can as it is thin sheet steel.
The mag below is pushed out of a die while hot and molten..like taking a dump after a night cruising bars in Tiajuana. Different metal to achieve this.
Once you recognize these mags for what they are... you will wonder why people who can't see it are such blockheads. I guess I am supposed to put in a smiley face here..Not.

Jerry Burney