Watching a movie on USA network right now about someone having dumped some Komodo Dragons onto a barrier island somewhere in the US. Just for giggles and grins, if such a thing were discovered and they were getting a group together to go kill them, what weapons that you already own would you take? For those that say they wouldn't volunteer, let's say they are offering $50,000 each for about 3 days work.
I think .223/5.56 would penetrate their skin, but I don't think it would be effective due to their weight and mass. Not a slam on .223/5.56 as I have several and think they are more than effective against humans, but this is a different story.
I would take one of my M1 Garands in .30-06, of course (.308 in Garand is blashphemy), because I think the much heavier bullet weight would be more effective against something that big. I don't own a .308 and think the .30-06 would be more effective in this case anyway.
As for a sidearm, either my Ruger P90, Sig P220, or USP45. All are .45 ACP. I would use FMJ +P in this case for penetration because I think JHP would not penetrate very well through their tough hide and would more or less flatten out near the surface.