Correct Slide for IBM?

[Mike in NC]

Charlie,

Again you are lucky, the most likely bolt for your IBM carbine is the one most commonly encountered, the round AOB marked bolt. IBM got into the carbine game fairly late so the round bolt was introduced fairly early in their production, somewhere in the 3.7 million range. By the time of your 3.849 million IBM had pretty much switched to only round bolts.