According to the link from Guns & Ammo Network :
http://www.gunsandammo.com/blogs/history-books/firearms-nicknames/
There are some word that describe average weapons and handguns:
AKAs such as “Heater”, Shooting iron”, “Smoke Pole” and “Persuader” are pretty easy to figure out, as are “Saturday Night Special”, “Suicide Special” and “Flyapart”, the latter a trio of terms to describe cheaply-made, inexpensive handguns intended for limited, somewhat specialized usage.
Hope it helps you.