Immediate action is the action taken to reduce the stoppage without investigating the cause. This action must be accomplished within 10 seconds, including waiting time, when the barrel is hot enough to cause a cook off. A cook off is the ignition of a round caused by the heat of the chamber without the firing pin striking the primer of the cartridge. One hundred and fifty rounds fired in a 2-minute period may heat the barrel sufficiently to cause a cook off.

If a stoppage occurs, wait 5 seconds. (The bolt must remain forward for the first 5 seconds because of the possibility of a hangfire.)

After the 5-second wait, raise the cover and remove the ammunition belt and the links from the feed tray. Pull the cocking handle to the rear, making sure the sear engages the sear notch in the operating rod; close the cover immediately; then return the cocking handle to its forward position.

During the retraction of the bolt, observe the round being extracted and ejected. If the round is NOT extracted, pull the trigger, attempting to fire the round. If the round does not fire and the barrel is hot, wait at least 5 minutes with the bolt in the forward position to prevent damage or injury to personnel in the event of a cook off. After the 5-minute wait, remove the round by using a cleaning rod inserted from the muzzle end of the gun.

When the round is extracted or when a round is removed from the chamber, inspect the gun and ammunition to determine the cause of the stoppage. After cleaning the machine gun, reload, rezero in on the target, and attempt to fire.

Table 13-1.-Malfunctions or Stoppages, Their Causes, and Corrective Action

Figure 13-16.-M60 machine gun disassembled into six major groups.