I see where you're coming from but I don't buy it. If the magazine seated, the round chambered, its that simple. There is no where else for the round to go, and if you visually and physically checked to see that the bolt was closed, there is no issue. The potential for out of battery bolts is a direct result of poor/insufficient lubrication, excessive fouling or other debris, and operators who f*ck with the bolt by partially retracting it to chamber check.
Lets look at your example in detail. You've just finished initial contact with enemy forces, there's a lull in the action. You decide to top up as anyone with some smarts would do. Now, if you pull the magazine from the rifle and notice rounds in it(a partial mag) and simply replace that mag with a fresh one. Why the need to CC? If you hadn't the time to top off you would have put full faith in the rifle still having a chambered round and atleast some available in the magazine, correct? Again, how did removing the partial magazine somehow equate to a loss of trust/belief that the rifle was not loaded. What evidence was presented to make you believe the rifle wasn't loaded? As I've said before, when competing or engaging other targets, you simply reload your rifle/pistol/shotgun when it runs dry at the very least, or sooner should the opportunity present itself. If your EMERGENCY reload, that's a reload from slide lock, or bolt lock does not include a CC, and an EMERGENCY reload is the most critical of them all. Then why bother with a CC at all? Tac reloads are done from cover at your discretion and convenience(for the most part) Administrative reloads are done at your leisure indefinitely. Neither of those cases, where most CC occur are critical loading events.
Some would say, "well if you have the time during a tac/admin load to CC then why not. Its just that little extra insurance." I say bullsh*t.. If a CC is extra insurance, wouldn't you want it when it counts the most, like during an EMERGENCY reload? Makes sense to me, but the reality is, you don't have time for that. Its an EMERGENCY reload for a reason, its an emergency. Your firearm is no longer serviceable and you're at great risk of injury/death(or losing the match). Chamber checking does nothing to ensure greater function or reliability in a firearm. Chamber checking is a mental assurance for the operator, nothing more.
That being said, if you insist on doing one for whatever reason. Checking rounds in the magazine is the most effective method, whether that be for a handgun or a rifle. Checking round position or witness holes along with removing and inserting the magazine has ZERO effect on the chambered round. Playing with magazines will not and cannot f*ck up that first round. It can however cause problems for the rest of the rounds in said magazine if the magazine is improperly seated. A poorly seated magazine is 100% operator error. As is an out of battery bolt after doing a CC via the bolt/CH.
Personally I subscribe to an entirely different method that is beyond simple. If a magazine gets inserted, the charge handle/slide gets cycled. Inserting a magazine IS loading the rifle/pistol and therefore the action must be cycled. It works on all semi autos, and it works every time I put a magazine in. It could be a tac load, admin load, or emergency reload, its the same for all. Its also the second half of your IA drill for a type one and two stoppage, weird huh? Same movements for several tasks. The loss of one round is cheaper insurance than running the risk of easing the bolt most of the way home. Seeing as how autos are designed to operate at speed and with great force, I am confident when I cycle the CH or slide and let it return to battery as it was designed to do, that the round did indeed get stripped off that properly inserted magazine(TAP TUG to confirm) and is indeed chambered and awaiting instructions.
There's a lot of discussion about methods of loading, unloading, IA's, RA's, CC, etc etc. At the end of the day, these movements constitute a very small portion of any shooting event be it an LE/MIL shooting or a competition. Focusing on sight alignment, trigger squeeze, and follow through is the bulk of the event. The sooner you put rounds on target effectively, the less of the other crap you'll have to do. It only goes to reason that focusing on the marksmanship fundamentals is far more important than the tertiary skill sets above.
TDC
You never had a gun or magazine related issue where the rounds werent being picked up, IE bad/dirty mag or your rifle short stroking and etc?
I rather CC and make sure my gun goes bang instead of click.
