I had my first "light strike" using the same .357 Fiocchi ammo as you. However, instead of taking the cartridge out, I re-cycled it and fired it with the Python. The round went off on the second try. I compared that round with all the other rounds I had fired and the primer strike was noticeably different. On the left is a normal strike and on the right is the light strike. I'm not sure if it came up like that because of the explosion, or if something was wrong with the primer.