safe a gun(Otherwise, if you just want to ‘safe' a rifle, engage any safety catch it may be equipped with, open the action, and unload the weapon in the most appropriate manner for the situation at hand. VLZ_58)
put on safe(There are about as many safeties as there are guns (well not really but there are a lot) so you really need to read the manual of arms for the weapon you wish to put on safe to know. However, following the first part of my answer is the safest way to put any gun on safe (even if the very first one was kind of a smart ass remark). VLZ_58)
place on safe(Remove the magazine, clear the chamber. Place the weapon on safe. As far as mechanical safeties go, these differ significantly by rifle model. VLZ_58)