Style over substance is always important to me. I know what firearms, and most mods, look like, and I style them to the character. Usually, however, I'll have one "Tactical" weapon that only cares about performance over anything else. "If you're not cheating, you're not trying."
Also, from what I've heard, the Launched Grenades arm themselves by an internal counter that counts the rotations the grenade makes as it flies. I heard about a REMF in Vietnam that got his hands on a "Dud" 40mm Grenade that he threw into his desk and forgot about. Every time he opened and closed that drawer, it would roll back and forth, until, one day, he slammed it in anger...
Launched grenades are impact detonation, so can't be thrown back. Also, from what I've heard, it's actually hard to "Cook" a grenade as the timers aren't exactly precise. "A Five Second Fuse will burn down in Three Seconds" is the phrase I remember hearing.