Hello DOP,
You have several clues. The construction of the shell base indicates its a more mdern round. Not likely to be black powder, and almost certainly a centerfire round with a primer. Additionally, the 'shoulder' at the top of the case is not common for older black powder cartridges. You will likely find the numbers 303 or 308 which would have been around when your logging cam0s were active
Your older black powder rounds will typically have a firing pin mark on the outside of the base, and have a straight case. Black powder cases were often large to accommodate more powder bulk, and frequently a heavy bullet. As cartridges and powder improved, you saw smaller cases and smaller bullets. Pistol rounds - say an old .44, will be about the same as a modern .44, but mNy of the old rifle rounds became more refined.
Read up on lever action or breech action and compare that to bolt action. Tge bullet design is often different in these rifle designs. Same is true of a semi auto pistol vs. A revolver.
Nothing above is absolute, but it will cover a lot of ground.
Zincoln