The enemy may be low on ammo. The important things are always simple. The simple things are always hard. The easy way is always covered by a sniper. If you are short of everything except enemy, you're in combat.
Incoming fire has the right of way.
RW will fail as soon as you need fire support desperately. Anything you do can get you shot, including doing nothing. HBs work both ways. The only thing more accurate than incoming enemy fire is incoming friendly fire. Make it tough for the enemy to get in even if you can't get out.