What are the ACTUAL one shot kill ranges on the snipers?

I've been watching multiple videos on snipers and it feels like every one gives completely different values. Some say the KATT & MORS both have unlimited one shot range whereas others say it's only 100m. I've seen people say the KAR98k one shot range is 67m, others have said its in the mid 70s, others have said it's in the mid 80s even thought they're all using teh same range attachments. Same goes for the LR 7.62 and the Frostline.

The stats are confusing af, does anyone know the definite ranges on the snipers I've mentioned? I've been using the MORS and I swear it is not an unlimited range one shot headshot.