[I'm confused about that...what do you mean "no broken 03 after 1929"? I don't understand what you're saying]
Most likely a reference to the US Ordinance Dept recall of all low-numbered 1903's in service for re-heatreating. The recall, however, doesn;t guarantee that ALL were done - as (for instance) the USMC didn't return theirs.
[I know that it is something of a rule of thumb to not shoot 03s that have an s/n under 1,000,000 but I do not understand this "8mm ammo" reference you have made.]
Some folks have forced German Mauser 8x57 ammo into the .30-06 chamber, and fired it, figuring "military ammo - it must be OK".
8mm-.323"vs .30" bore.