When the idea is to not make any noise, racking the charging handle is counter productive.
I can lower the bolt on a live round slowly and get it ready to go without a charging handle. The real question is, why can't you?
When someone is trying to kill your a$$, the noise isn't an issue.
If you are slowly lowering an AR bolt, and not checking for crossover, you are fundamentally ignorant of how to operate the weapon. Just because stupid schit works most of the time doesn't mean it isn't still stupid.
