It was probably me from the T/C Rifle section maybe? I should clarify. It is illegal to CREATE any new rifle or pistol round with a bullet diameter greater than .500" (could be a few thousandths leeway up, but I dont think so.) Any bigger and it gets a "destructive device" classification from our good friends at the BATF(E). What this means is that guns can be chambered for greater than .50 caliber, but the chambering itself must be of prior conception since the law passed. So, if there were actually someone crazy enough, you could have a handgun chambered in 600 nitro express. Same with a rifle. But it is not legal to make a brand new 60 cal chambering (say a 600 Smith and Wesson Magnum, for example.) Of course California has different rules and regs.
Brian M.