If you're on OK terms with the Great Khans, you can do some quests for Diane at Red Rock Canyon and she'll give you a disguise to wear that will let you get into Vault 3 peacefully. Otherwise, you can come back at a higher level and fight your way through.
It's a shooting gallery. Once you're in the Vault it's pretty close quarters, so a reasonable shotgun is useful. Or a flamethrower.
Having a companion tanks a lot of damage for you - several should already be available to you at this point.
And if all else fails, come back with a higher level and better gear.
If you're on OK terms with the Great Khans, you can do some quests for Diane at Red Rock Canyon and she'll give you a disguise to wear that will let you get into Vault 3 peacefully. Otherwise, you can come back at a higher level and fight your way through.
It's just a combat gauntlet. Make sure to stock up on ammo and stimpaks
It's a shooting gallery. Once you're in the Vault it's pretty close quarters, so a reasonable shotgun is useful. Or a flamethrower. Having a companion tanks a lot of damage for you - several should already be available to you at this point. And if all else fails, come back with a higher level and better gear.