A cartridge for a cartridge-loading motion picture projector has an opening or slot therein for receiving portions of a film feeding mechanism that is used for extracting film from a film roll within the cartridge and for feeding the film to automatic or self threading devices of the motion picture projector. The cartridge has a deflectable member, such as a spring or tongue, positioned with respect to said opening so that entrance of the film feeding mechanism into the cartridge deflects such member from its normal position to a film guiding position within the cartridge. The deflectable member is located in the cartridge so that during rotation of the film roll in an unwinding direction by the film feeding mechanism the leading end of the film engages the member and is guided by it to a tip end of a film engages the member and is guided by it to a tip end of a film stripping finger. The finger then lifts the leading end of the film from the roll and delivers it through a guide slot or channel to automatic threading devices of the projector. The apparatus of this invention also comprises improved film feeding mechanisms that are useful with the cartridge disclosed herein as well as with other cartridges. Such film feeding mechanisms comprise means for deflecting the deflectable member as the mechanism enters the film cartridge, and means for narrowing the normal slot or channel between a film drive belt and the film stripping member, thereby to improve film feeding operations of the mechanism and to deliver film from the device properly oriented for reception by an automatic threading device of the projector.