There are several variations of these both in size and appearance, and yes they ought to be more popular amongst collectors as these are really nice
The makermark had also several variations:
F.M.Mattson Mora
F.M.Mattson Mora Sweden
F.M.Mattson AB Mora Sweden
FMM Mora Sweden
Variations by FMM's modelnumber:
model 710 Small, simple model. Double crossguard, w/o clamshell. Overall length 285 mm
model 720 Double crossguard, with clamshell. Overall length 330 mm
model 100 Single crossguard, with clamshell. Overall length 330 mm.
model 730, model 110 Double crossguard, with clamshell. Overall length 370 mm
They were never allowed worn by uniformed military personnell.
My sources are from a swedish bajonet collector,
www.holmback.seBest regards,