You are not allowed to harm your body. Smoking harms. Smoking kills.
There are two things here, the harming and the killing. The killing is for a routine smoker. The harming is even smoking one.
Also, just an aside to 147 who posted that most gedolim would be in favor of banning all guns, I’m sorry, but that is not a Jewish perspective. You have been brainwashed and I am going to assume you live either in the NY or LA area. Gun control is not a Jewish concept.