Weapons on Stage

UK

In the UK, the Health & Safety Executive has produced a guidance note called “Management of Firearms and Weapons in Film & TV Productions“. This note covers the Health & Safety issues connected with weapons, but there are other legal instruments that should also be consulted, including the Firearms Acts, the Violent Crimes Reduction Act 2006 (VCRA) and the Crime and Security Act 2010. The local police force must be informed if there are any weapons audible or visible to the general public (not in the theatre).

A fight director should always be consulted where any weapons are used in a fight situation.

USA

Rules on gun use on stage vary from state to state. 
Real weapons (even if they have parts removed) are never permissable on stage. 

Accidents

There are several well-documented instances of actors injuring themselves with weapons.

In 2008, Daniel Hoevals accidentally slit his own throat on stage in Vienna, when a fake knife was swapped for a real one without his knowledge. [News Article]

Guns on Stage

Many theatre companies do not permit the use of firearms on stage that are capable of firing blanks. 
Excellent dummy weapons are available which look good, but are not capable of firing anything, and cannot be modified to do so. 
Even dummy weapons should be kept under direct supervision of a member of the stage management team, and should be issued direct to a performer, before returning it to a locked cupboard for storage between shows. A gun should never be left on a prop table unsupervised. 

Blank-firing weapons can cause severe injury or death, and so these should not be used on stage unless under professional supervision, by someone qualified or certified to handle such weapons. 
This website cannot offer advice on using blanks on stage, other than to say that there is really no reason to do so. Sound effects are more reliable and effective, and have no risk of injury. The actor can mimic the effect of gun recoil, and a fight scene can be choreographed to work well with sound and lighting effects. 

Retractable Knives

Current professional advice is that retractable knives (or other weapons / tools) should not be used on stage, due to the risk of them jamming and not retracting. Any fight using weapons should be supervised by a fight director, who can ensure the choreography is safe. 
Remember that the audience is usually a fair distance from the stage, and that all on-stage props only need to look real from the audiences’ perspective.

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