This sound effect can be found on Dynamic Range Sound Effects Library - CDs 1 & 2, which was made by Sound Ideas. It was recorded on June 12, 1989 by Craig S. Jaeger & Edward M. Steidele for Warner Bros. Records. Links: https://soundeffects.fandom.com/wiki/Sound_Ideas,_GUN_FOLEY_-_HANDLING_12_GAUGE_MOSSBERG_SHOTGUN_RELOADING#Audio_Sample