Learn the emergency pistol reload from a former Tier One special operations shooter: it is one of the most important things to learn to be prepared for a gun fight.
This drill is called the emergency reload because you are under fire or there is an immediate threat to your front. While keeping your gun in your "work-space" - the area just in front of you while looking over the gun to keep your eye on the danger area - you are dropping a mag and getting another fresh (fully loaded magazine) back into your pistol to get rounds downrange as soon as possible.
One of the most important aspects of this drill, like all the other drills covered, is to build muscle memory by practicing it again and again. Note also how Mr. Lamb has his extra mags setup and facing in his mag carrier so that he cuts down on time lost with the ability to quickly index that next magazine into the gun.
You can practice this drill dry (ensure your gun is proven safe, unloaded magazines, and point in a safe direction) by just learning the most effective way to drop and get a new mag into the magazine well on the pistol. After that, move to the range and practice it live. You can do the same as this video demo by only firing a few rounds from each magazine and doing a emergency reload or you can simply fire the mags empty and go through the drill.
The final point is to do this drill deliberately and combine all the other drills you have learned, start more slowly and build speed with practice. Concentrate while doing it to maintain your accuracy; there is no point doing a drill if you start missing the target.
As always, practice this to build muscle memory, train often and train hard. On the next installment of The Armed Citizen, we will discuss another drill called the Tactical Reload.