approximated but to give an idea
I have 2 #73's and they are like 8 but it's OK on the knife, more usable but a 6 would be preferred
the 66 mink is a 2-3
66# northy jack is 6
the 23# was a 8-9, pretty pretty hard and the half stop is scary
36# sunfish, not "hard" but needs some force, spring and blade are BIG, 7-8
53 northy rancher 6-7
48#'s 3+
53 furtaker 6
some I've seen/bought for friends
89 gambler, 2-3
lockback 72 in clip and wharnie, 1-3 and smoooooth
various 73# from 7 to 8+
2x# good at 3-4 I think
the 73#,23# and 36# have thick springs, big blades and are thought for heavier use so tough springs are ok, little attention is needed, they're the hardest I've come across out of the 20+ that I've handled
the others are all fine for me, some more some less, 66 and 48 are a joy to use and open, the 53 rancher is overbuilt and on the hard side but it's understandable, the 53 furtaker is just fine for the size, no problems
I edc the 73,48,66 jack, 53 furtaker often and all of them are fine
IMO you need practice in handling and often some attention but they are not scary or dangerous, not more than a SAK
hope this helps, just some cents of mine
Maxx