slots for mods

[@nd]

I have just received a variation from the MET for a mod, it specifies a .308 moderator,(this is the largest caliber on my FAC).
I have a 6.5mm rifle slot on my FAC which is what i wanted the mod for.
When buying a moderator is it just entered onto your FAC just as a moderator or is it entered as a specific size IE .308 moderator or 6.5 mm moderator etc

[safetyfirst]

It's random. Mine says C/F sound moderator... But the vendor makes the decision what to write, probably to match the slot it's filling.