During a test my friends and I were doing of the new handcuffs, we learned that our prisoner was still able to access his Pistol, place it into his hands and fire the weapon in random directions.
While going through his inventory, I took said pistol and was able to run around and fire it, while my prisoner still held "his" pistol and fire.
Give a player a pistol
Handcuff said player
Have prisoner place pistol into hands after cuffed
Have prisoner fire
Take pistol from prisoners inventory
Notice his pistol still in possession
While in this position, my prisoner was not able to move nor actually aim his gun.
After logging out and logging back in, the handcuffs were off and the handgun was NOT in his inventory.
Nearly got myself and a buddy killed by another friend who was able to shoot his pistol albeit being handcuffed.
If the handcuffed have a handgun on the back pockets of him pants.... then this is a Feature, not a bug. In real life, it may be possible.