FWIW you can argue tactics till your blue in the face - one technique is not necessarily anymore right than another as long as they work -- the same goes with weapons drills.
The idea is to get your rifle/carbine (or pistol whatever) back running as quick as you can - as well as ensuring that you can comminicate to your teammembers you have an "issue" and that your sector is covered while you cannot.
I got asked some comments on the "beer can grip" method
I took some pics -- sorry they suck
The only time I use this method is reloading from my redimag -- as I find it a lot easier (for me) to use the index method for reloads from my mag pouches.
GunFighter was teaching beercan -- and I beleive its due to the MP-5 skillset as I beer can with an MP-5 -- but index on the M4/C8
Beer can is very good for push pull insertion
Why call it beer can - well a picture is worth a thousand words
Mag pushed up into mag well and locked home
Mag pulled down to ensure its locked (note my Gemtech can in the background on my rifle rack)
Thumb engages bolt catch
Keep in mind I use a redimag (and my M4 is a in-theatre conversion to auto)
My IFF flag and closeup of the GemTech HALO