I'm trying to kill Benny, but Boone doesn't have a weapon. can you sneak multiple weapons into the casino and how big of weapons can you sneak in.

I've been able to smuggle .22 silenced, grenades, and small knives.

It depends on your Stealth skill I think. I got in with my modded .357 and grenades.

I didn't take anything in, picked up a couple of pool cue's and beet him him to death in his room.

As long as you have 50 or 55 sneak, you can get past security with any amount of "holdout" weapons. This includes most handguns, grenades, throwing knives, some unarmed and melee weapons. Leveling sneak, I haven't seen any improvement in this regard, which leads me to believe that it's nothing more than a requirement.

The best weapon I've got past casino security so far is the Mysterious Magnum (.44). Ranger Sequoia (.45-70 Gov't) didn't do the trick, and I haven't got a 12.7mm pistol yet but I'm guessing it doesn't work either.

Keep in mind there's more than one way of killing Benny. You can kill him in his sleep with Black Widow (possibly Confirmed Bachelor), you can pickpocket his ammo so he can't use his pistol, blow him up, etc.

The sawed off 12ga double barreled will make it through as well.

Oooh, nasty. I'm beginning to become fond of shotguns in this game; never had much use for them in the previous game, really.

I got in with 8 grenades...4 plasma, and 4 frag. I didn't get benny, but he sent his 4 henchmen after me. There was a SMG in his vault, and with that and the grenades, I was able to kill them all, but it was a close thing.