Long time ago when i was an armorer in the US Army and later in the reserve, I worked with the Model 1919A6 which was very well liked. As the M60 started to replace the old BMG, we received new examples that had the R stamped indicating the feed ramp was altered to prevent a live round from striking a chambered round as I remember.

When a firing pin broke in the field, the weapon was very difficult to take apart and had to be returned for repair. I saved a broken firing and spring as a reminder. Also the spring that held the trigger group to the receiver would come off and get lost tooAttachment 106328