You say a battle, so assumably there are more people opposing zombie apocalypse/renegade looting than just me.
Hrmm...
Sniper rifle, a Skorpion sub-machine gun, too much ammo for each, four frag grenades, a sledgehammer and a mesa, probably only about a foot long. The best thing about snipers is that you pick a spot and stay there. If you have to move, you move incrementally, scouting first then moving your long-term supplies.
Sniper rifle keeps you out of trouble and has enough stopping power to put anybody out of their misery/unholy compulsion, the SMG is good for on-the-move and surprise attacks, four frags is enough to clear a house of dangers without being too much of an explosives hazard, sledgie is for intimidation and utility (any locked door short of being purposefully reinforced goes down. End of story) and the mesa (german knife, very heavy and not often used for stabbing) is as much a bush-whacking tool as it is a weapon.