>>63829842Aside from correcting bratty grunts who use a thumb-high magwell grip, the reciprocating CH can also snag on pieces of the environment like VTAC barricades if you jam the rifle magwell-deep into it when you're stabilizing the gun for a longer shot. It is largely theoretical considering how far back on the receiver the SCAR's charging handle is, but that, in turn, leads to the end user having to install an aftermarket CH or be unreasonably diligent in his optic selection and placement to avoid racking his knuckles against his optic's mounting hardware.
The problem, ultimately, isn't with reciprocating charging handles in general—the AK and Garand have them, and they're obviously fine—but with the SCAR's implementation of the concept, which is only partially mitigated by the recent NRCH "upgrade".