"biggest problem"!
That's more than a "problem" -- that's a freaking death blow to the poor grunts relying upon the failed weapon.
There's a certain "Pucker Factor" when one is on a Night Assault, tens of klicks from any backup, with tracers going both ways, and the weapon you meticulously cleaned a few hours before decides to jam with the shell casing stuck in the breach!
Been there, done that!
One of these days, the Powers that be should, hmmm, "enjoy that feeling" before they vote to choose the next generation of "huntin" implements!