I have not fired my Rock Island s/n 64145 although the bore is really nice, I do shoot two other four digit Rock Island rebuilds, both having early SA pre WW1 barrels and early parts. I used an auxiliary chamber adopter to fire 32 ACP and 32 S&W short, now I can also shoot 32 S&W Long. These sub caliber inserts work out nice in your indoor pistol range or basement range. Interesting that the 30M1 carbine is not a good choice because of the velocity and bullet weight ! I noticed that I posted my four digit SA by mistake
My favorite early 1903 is a Springfield s/n 160963 with a SA 2-07 dated barrel and a "no bolt" stock with the CCV cartouche and inletted just like your Rock Island stock.Attachment 97013Attachment 97014Attachment 97015