I will.
Situation #1: If you've just chambered a cartridge and the slide is out-of-battery because the just-chambered cartridge jumped into the chamber ahead of the extractor, a slap to the back of the slide will remedy the situation. Quick and simple. (I.E. : The extractor does not engage the case rim. A simple tap/rack would only result in a doublefeed. While you could remove the magazine/rack/replace the magazine/rack/bang, all you really had to do was to slap the back of the slide.)
Situation #2: If you are doing a chamber-check. The last step of a chamber-check is a slap to the back of the slide (to ensure that the slide is in-battery).
If you're chambering a round and its not during a shoot, there is no need to save time by slapping the rear of the slide. Eject the cartridge in question and inspect the system before carrying it. If the slide fails to go into battery during a shoot your IA will take over. If the IA fails then remedial action will solve the issue. Forcing an unknown round/debris into the chamber under the belief it is a round that has jumped the extractor is bad form.
Chamber checking is unnecessary and can be accomplished by use of a loaded chamber indicator, the good ones include a tactile portion that protrudes when a round is chambered. The use of witness holes in the magazine is also a sound method of ensuring a round is chambered. You could slap the rear of the slide but have you done that on a pistol with exposed hammer? Do you aim for the side of slide or just eat the hammer in the palm of the hand?? Another issue with the use of slapping the slide. How does one perform such action when firing one handed as if one were wounded or otherwise without the use of the support hand??
Cycling the slide and allowing full compression of the recoil spring will ensure your pistol chambers a round in full battery. This action is what one relies upon during operation of the pistol, so a slap to the rear is not necessary.
How about the other "methods" taught my Magpul???
TDC




















































