First of all I question the need for Barrel Porting or a Muzzle Brake on a .30-30 Winchester Contender Barrel. In my opinion the .30-30 Winchester in a Super 14 Contender does not recoil enough to warrent the need for either of these. I have shot some pretty stiff Handloads (125gr. Nosler Ballistic Tip at a Muzzle Velocity of 2400 FPS) from Super 14 .30-30 Winchester Contenders and the recoil was not all that much more than a light framed .357 Magnum revolver.
With all of that said typical Barrel Porting (in the form of Mat-na-Porting) is nothing more than properly shaped, properly placed slots cut into the barrel near the muzzle. These serve to lessen felt recoil by controlling muzzle rise during the recoil process, thus redirecting the escaping gases thus changing the way the gun recoils.
On the other hand a Muzzle Brake normally has a series of holes drilled around the circumfrence of the barrel near the muzzle, and as such displaces a larger amount of the escaping gases. In addition most Muzzle Brakes have an "Expansion Chamber" to trap these gases and control the amount of gases prior to their exiting the barrel. What all of this does is to increase the amount of gases redirected and actually reduces the rearward push of recoil. Depending on the size, location, and angle of these holes and the size and shape of the expansion chamber a gun can be made to actually move forward during recoil. Yes I know it is hard to believe but it can ideed be made to work this way. The down side to Muzzle Brakes is that they dramatically increase the amount of muzzle blast to the shooter (or anyone else nearby).
I don't remember the web address, but there is a site available that has a lot of info on Muzzle Brakes, their design and usefullness. Just type Muzzle Brakes into your search engine and hit search.