I found a matching shifter knob replacement in a box i got at an automotive auction. I installed it for the transfer case on my diesel Ford, the thing rattled a lot even after locktite was applied to all fasteners. Nice looking piece, but silly. And the "secret compartment" it's hollow and unscrews at the top seam, that's where you hide your weed! You LEOs watch for that!
Suicide knobs will disembowel you in a crash. Here in CA they are only legal for handicapped. Damned nice when backing up though,
You had me confused. I was trying to figure out what purpose one of those knobs could possibly serve on a gun.