Lee,

It's not hard, it's impossible with fly tackle, and with most conventional gear as well.

If by some bad luck you try to hook a bass at the moment it is in 'crush' mode, it just won't work.

They don't make a fly rod that will allow you to hook a bass at that time. Don't matter how hard you try to pull.

On those fish, you just have to hope that the fly grabs something on the way out and you get a pressure set from the fish pulling.

Good Luck!

Buddy