If it were truly done by Springfield... presumably before heat treating... then why would it need to be serial numbered?  I'm just asking out of curiosity.  It seems to me that a cutaway demo model would not have a serial number.  Also, the bullet looks more bronze/copper jacketed than cupro-nickle, which appears almost dull silver in color.  I'd love to know what head-stamp is on that cartridge.

Interesting!