In the early game, Metzger can be a real pain because there are A LOT of people you need to kill. I mean, you don't want to pay him all that money for Vic, right?
There's a very simple way to kill a majority of Metzger's gang. It requires a decent gun skill (preferred), your best gun and a bit of ammo. I suggest bringing your most powerful weapons and all their ammo. You might need it. You also need a stick of dynamite. You can easily find this in Redding. Just steal it from the General Shop's Owner (SAVE BEFORE DOING THIS!). Also, don't bring a companion.
I'll list the above steps in point form, too.
YOU NEED:
-Decent guns skill
-Any gun except a pipe rifle, with lots of ammo. I recommend all your guns you can carry and their ammo.
-A stick of dynamite. You can steal this from the shop owner in Redding. Save before attempting to steal, though.
-DO NOT bring any companions. They might die from the dynamite explosion.
Be sure to save before doing ANY of this. If you mess up, or need more ammo, you can always go back and re-do this scenario, or get more supplies.
Go to Metzger's slave house, and stand just about in front of the door. You should be outside! Now, rig the dynamite so it explodes in 3 minutes. Drop it. IF you are caught, reload, and try again. Once you successfully drop it, go stand a little far from the dynamite. You should walk a couple hexes south. Now, you should be positioned so that the door is in your firing sight. You should be able to shoot inside the door frame. Now, start killing the guys outside the house. If they run away, let them be. Now, some of the slavers will line up inside, behind the door frame. Begin shooting them. They won't fire back (except Metzger).
Once you finish killing a majority of them, kill the ones outside, and then wait until the dynamite explodes. If it exploded a little earlier, it's okay. There might be a guy or two who tries fighting you, but everyone else should be running from you. Now, proceed inside, and kill any surviving slavers. If you don't have Vic, get him. I highly suggest looting EVERYTHING from the dead slavers. You can give the spare guns to Vic, and sell some of them. If you can't hold onto everything, let Vic do it for you.
Now, open the slave door, and talk to one. Say they're free to go, and get 1250 XP. Now go talk to Rebecca in Becky's, and get $1000.
Point form:
-Don't have any companions with you
-SAVE before doing this.
-Rig dynamite so it will go off in 3 minutes. Drop it so that it's outside, and in front of the door frame. Make sure it's not so close inside, not too far outside. If you get caught, reload, and try again.
-Walk a few hexes south, so that you can shoot inside of the building from the open door. Make sure you aren't too close to the dynamite.
-Begin shooting at the guards outside, this will draw the slavers that are inside the building near the door frame. If any of the outside guards still try and kill you, kill them.
-Begin shooting at the slavers inside. They shouldn't shoot back (except Metzger might)
-Once the slavers inside refuse to come close to the door frame, kill the ones outside, and then wait until the dynamite explodes (if it hasn't). Then proceed in and kill the surviving slavers.
-Talk to Vic, and tell him to join you as a companion. Loot ALL of the slavers, and put their things on Vic. Vic is good with guns, and this entire thing loads you with about 100 JPH and AP rounds.
-Once you loot everything, open the slave pen door, talk to a slave, and tell them "They're free". This awards you 1250 EXP (around).
-Talk to Rebecca in Becky's. She will give you $1000. (You also get +100 Karma).
NOTES:
-Any of the Slaving Caravan random encounters will be hostile to you after killing Metzger.
-South is the bottom right corner.
-The guns on the dead slavers may disappear after you leave the zone once. Careful!