For those that have never been exposed to advanced training, ejecting a partially loaded mag ( let’s say you fired 6 rounds of 8) and inserting a fully loaded mag (with one in the pipe) if you feel there is still a treat is called a TACTICAL RELOAD.
You put the ejected mag in a pocket,stick it in your belt or anywhere you can get it quickly in case you run out of ammo. The 2 rounds left in the first mag could save your life.
I am sure there is YouTube video that covers this subject.
AWAYS carry a extra mag if you can!!!!

Be SAFE and shoot often!