I just got into primitive fire making and am starting out using Magnesium Fire starters. I noticed that while my DCDM worked well at shaving the Magnesium, the back of the blade wouldn't spark when pushed against the rod. Any ideas why? Is it the Steel used, possibly Double Cut? It worked good on stainless, and better using high carbon, but not the back of the DCDM. I did try to use a small portion of the blade, and it worked, but don't want to mess up my sharp blade.

Any ideas?