I'd like to remind people that not all killing is murder.

Would you call the Allied forces in WW2 "murderers" for killing Hitler's
troops? And now psychologists/doctors/psychiatrists are acting like Hitler.

Firearms are effective, but banned in some places; however, this book
describes in detail the manufacture of munitions from seemingly innocuous
locally available materials:

http://www.fortliberty.org/military-library/improvised-munitions-handbook/improv
ised-munitions-handbook.shtml