Hi Matt thanks for the great info. You are correct about the flat checkering. I have decided to leave the checkering as it is. There are some areas of compression and missing flats but I'm OK with that. The barrel length and external magazine info was interesting and it makes sense.
I have some Hornady 160 RNSN projectiles as well as some lighter spire points that I use in my 1903MS. I will be careful with the headspacing and pay attention to it. Thanks