Gunplay is the act of using either a loaded, or unloaded firearm during BDSM and sexual play. It can be used as a penetrative object or a prop.
More About Gunplay
This is one of the most taboo and risky forms of BDSM play. The gun takes the place of a penis in most acts, but can also be used as a prop weapon in extreme edgeplay scenarios. It is usually unloaded and used as a dildo of sorts for vaginal or anal penetration. It can be used orally as well. The use of firearms in BDSM is controversial. It is considered taboo at best, and for many it is too risky even with an unloaded weapon.
Gun play is a form of extreme edgeplay classified under RACK or PRICK play styles rather than SSC (safe, sane, and consensual).