Swedish Mauser "dot matrix" stamping on bolt knob

I've got a "mixmaster" M96, last three numbers in serial "406". The butt plate matches and the bolt knob has a "406" dot matrix type stamp on it. The bolt shroud is not numbered and the safety and cocking piece match, but are a different number. No other matching parts.

I've never seen a "dot matrix" number on a Swedish bolt and wonder what it means.

Anyone ever seen this before?

https://www.milsurps.com/images/impo...VD45jpg1-1.jpg

My guess is the importer did it but why, no clue. I never ran into an M96 that wasn't all matching so must be the bottom of the barrel for imports.