For me the perfect weapon in front line combats would definantly be explosives. I would have like 50 grenades on my person and I'd have a rocket launcher with a littler robot person that followed me around that manufactured rockets so I would never run out of ammo. I would rush the lines firing non-stop and releasing grenades left and right.
Seriously, if all you had was a high caliber rifle and you bust into a room and by some chance they have a fast enough reacting time, you're pretty much giving them a chance to shoot at you considering there's more than one and you have only one gun.
If it was me, all I would have to do was throw about five grenades and the rooms cleared in a matter of a few seconds. But then if I had to retrieve information from the room I would throw a flash-bang grenade and run in there with my machete.
All in all, using anything like that is risky and should only be used by professionals like me.
