Suicide seems to be illegal in America, yes.
Actually one of the safest methods to kill yourself isn't by a gun but by putting explosives in your mouth. At least small calibre guns might fail their purpose, with you ending up as a vegetable.
Overdose is harder than you might think, if you don't, once again, go for the illegal stuff. Most drugs prescribed, unless you already have an almost deadly disease won't kill you nowadays. When each and every MD prescribed strong barbiturates, 30 pills were often enough.