YouTube has long had policies in place which prohibit videos encouraging or instructing violence or harm, and now video tutorials on a type of gun modification called a 'bump stock' have also been added to that list. This comes in the wake of a mass shooting in Las Vegas which involved hundreds of rounds being fired rapidly from a weapon, and resulted in the loss of at least 58 lives, as well as hundreds of injuries. The ban on bump stock videos stems from the fact that this dangerous modification was reportedly used in the shooting. Bump stocks are technically a legal modification for a firearm in America, but YouTube has seemingly determined that they are not suitable for the video-sharing platform.
It is worth noting that gun modification as a category of videos has not been banned from YouTube as of this writing; the policy change only affects bump stocks, due to the danger inherent in such a modification. There are many types of modifications that can be made on a variety of firearms to change their looks, enhance their performance, and change the way that they feel or act, among other things. Not all gun modifications are necessarily tame though, and some are more dangerous than others like for example a bump stock - where the point is to modify the weapon so that it is capable of vastly more rapid fire than would otherwise be possible. While there are numerous reasons as to why one may want to perform such a modification, the fact that it lends itself to such activity is seemingly enough to earn its removal from YouTube's video library.
Videos showing how to use a bump stock are far from the only dangerous and controversial content online, and big internet companies have been feeling the pressure in that regard lately. All sorts of user-generated content, from hate speech to propaganda, is getting big tech firms in trouble, and prompting them to step up countermeasures. With enhancing the AI that detects and removes such content automatically and the addition of more review staff to police content, being two such examples.