A friend Shawn N. shared this photo. Did you know that a .45acp spent casing can be used on an original John Moses Browning design 1911 as a recoil spring plug. Why would you do this? In case you lose your plug out in the field, you can use a spent casing in the interim and get the gun working again.
Pretty neat bit of practical trivia. What other field repairs have you heard of or used to get a gun back in the fight?