Theydetachable mag haspostives and negatives.

Detachable Mag:
Positives. You can pop in another mag and be fully loaded in a hurry. If you need to do that then you may want to head back to the range, but nonetheless it is a fast reload.
Negatives:
It is one thing that could be left at home or lost, turning your gun into a single shot.
It can be ackward if you like carrying your gun with your hand on the foreplate.
I am not sure if this is a problem: I reloaded a 300 win mag Tikka for my brother and the detachable mag would only let me load out the bullets so far. The detach mag may not get me to the lands. Not sure about that though.