When determining the cartridges a rifle can feed and fire, what goes into determining the rifle's action length and, therefore, the maximum OAL for a cartridge? I'm specifically thinking along the lines of the human-powered portion of the action, as I know the magazine box will provide an upper limit of its own. Is it bolt travel? The length of the ejection port?

My question stems from a piqued interest in .375 H&H and that conventional wisdom is that it is too long a cartridge for the 110. Indeed Savage does not currently carry any guns in that caliber, though this was not evidently always the case. In one online discussion I found in my research, a fellow measured his standard 110's bolt travel and ejection port as longer than the .375 H&H OAL of 3.6". That leads me to believe that it is the magazine that prevents Savage from producing rifles in that chambering, but is there something else mechanical preventing it?