JCP.
Your Remington Rolling block action is properly identified as the Model 1902 or M1910 number 5 action. It is almost dimensionally the same as the earlier Number 1 black powder action, except that it was made of stronger steel specifically for smokeless powder cartridges, and takes a larger barrel shank than the old number 1 action.
If your side-handle breech block is original to the action, that is an additional clue to it's identity. Starting with the M1897 RRB, the side-handle breech block was used. The most commonly encountered number 5 military actions were in 7x57 Mauser caliber carbines and rifles made for the south and central American markets (Mexico, Bolivia, Honduras, etc.).
The action was reputedly chambered for 7x57, 7.65x53, .30-03, 8mm Lebel, 7.62 Russian, .30-30 Winchester and .30-40 Krag. I have never seen the commercial chamberings except for one .30-40 carbine obviously made from an M1903 Springfield barrel and a .43 Spanish action (NOT a good idea).
In answer to your question of how strong the action is, it is the preferred action for rebarrelling to a BPCR in rimmed cartridges such as .45-70, .45-90, .38-55, etc. It is suitable for rebarreling to 7x57 class rimless cartridges, according to the late Frank De Haas, "Mr. Single-Shot". He also strongly advised against rebarrelling to high-intensity calibers such as .222 and .223 Remington, or any of the small to medium bore high velocity cartridges such as .243 Win, .25-06, .270, etc.
In summary, it's probably best (and safest) to use that action for blackpowder straight cases, or modest smokeless loads in the same cases. The bottle-necked calibers don't get good case life due to the "springyness" of the action.
HTH
John
