Kahunaburger said:
At that skill level you may be able to do Vault 34. It's southwest of Vegas, and highly radioactive. Basically, the vault's gimmick is guns for everyone, so if you make it to the armory you will basically be set for the rest of your playthrough.
This. Only yesterday I ventured into Vault 34 for the first time (because I heard of the Armoury). Believe me when I say this:
It is definitely worth it, no matter what weapons you use! Honestly, I had to make my companions carry all the guns and ammo because I was so over encumbered. It ain't easy getting there though, I used a radiation suit, countless Radaway and Rad-X, and I still just barely came out alive (granted I was in there for quite a while but the Vault does have a lot to offer). I was at about level 18-20 when I went through this Vault.
Other than the vault, Gun Runners next to the outer walls of Freeside, they sell fantastic weapons and mods so long as you are a high enough level. I think they are the best gun store in the game.
My character is currently level 25 and these are my weapons:
1. Laser Rifle (w/ mods for a scope, and a damage increase).
2. A unique Marksman Carbine (which I found in Vault 34).
3. Riot Shotgun (this is a fantastic weapon if you like shotguns).
4. Anti Materiel Rifle (takes down Deathclaws in one hit w/ Armour piercing rounds (with 100 gun skill)).
5. Grenade Machine Gun (I don't use this as much, but I have it for groups of enemies mostly).
Out of all those guns I would definitely two of those weapons. The Marksman Carbine, and the Riot Shotgun. Both very powerful and fun to use weapons. I would recommend the Anti Materiel Rifle as well, but ammunition is really expensive, and weighs a ton, also the gun is hard to repair without the Jury Rigging perk.