Im unable to do back squats right now (no rack, work out at home)..I was curious to know how the hack squat compares to the back squat in terms of how much weight you can lift. I know grip strength comes into play with the hack, but if you can do say 400, how do you think that would translate to the back squat? Would you be able to more, less, the same?? Or is there no correlation between the 2 moves?
Personally, I don't really think that there is a direct corelation between the two.
The hack squat is specifically designed to target the quads whilst the back squat hits the posterior chain far more.
I think in the absence of back squats a good substitute would be snatch grip deadlifts (although you never asked that!)