This is really neat. An X-ray of an M1 Garand stock with a radio transmitter inside.
Developed in the 60s for use in the covert war. The story is, an M1 would be left some where VC or PAVN troops would fine it after a fire fight with the trigger guard unhinged. They would pick it up and take it back to base areas and latch the guard. It would start transmitting and after it was stationary for a while it would be hit with an Arc Light strike. ( B-52 bombing). I can’t confirm if it was ever actually used or not.