When a cartridge case ruptures in any way, be it a soft case head or splint in the case the gas escapes into the action. When that happens the floorplate is blown out, the stock is split and most likley the extractor is blown off.
The rifle is out of service regardless if it was a low-number or high-number.
If I understand the design of the 1903 correctly it was made to withstand cartridge failure. It very clearly stated that the rifle must pass firing two each of the following defective cartridges when designed.
1.Crossed filled on head to nearly the thickness of the metal.
2.Cut at intervals diagonally through the extractor groove.
3.With four longitudinally cuts the whole length of the cartridge shell from rim forward.
I think that today many people believe that any case failure in a low-numbered action will result in the action breaking. IMO this is just not true.
