I am building a new rifle starting with a custom action. I was wondering if someone could point me towards some info regarding what to look for in an action as far as dual port, single port, bolt dia. etc etc.
Just look at the options. A dual port allows you to handle cases out of either side, yet still gives the extra stiffness of 'covered' action.
A Remington action has the top of the action open so handling rounds in the action itself is easier.
A round bottom that matches the Remington footprint is a plus in that most of the stocks out there are geared toward that. Savages are close but different enough that a basic Remington aftermarket stock isn't going to fit it very easily.
<span style="color: #000099">Added: Savage has a drop bottom magazine as does Remington. But the majority of</span> <span style="color: #FF0000">{high capacity}</span> <span style="color: #000099">DBM's that are known to work are for Remingtons. It will take some 'fit and finish' for another brand.</span>