For some reason, all of a sudden i had Boone's rifle and Boone would only use his machete. He would use melee weapons I gave him, but wouldn't use any gun i gave him. I couldn't give him his rifle back, either. I also dropped his gun, seeing as it was useless to me.

So please help, how can i make him use his rifle, or a gun I give to him.

Occasionally companions weapons bug out like that. You can't use it or give it back. On PC there's ways around it but....beyond loading an older save game (and leaving companions outside of casinos), not much option on consoles I think.

to make them use a weapon you give them, you have to also put the ammo for the weapon type into their inventory and keep it stocked up. Only companion's default weapons (which is now unavailable to you) have endless 'magic ammo.'

I used to have this bug, but patch 1.02 seemed to fix it for me.