I have never really done box squats except on the speed day of the Westside beginners program. Usually I do full squats as low down as I can go, way below parallel. My usual for that is working up to 275-315 for 5 reps. I tried doing heavy box squats today and did WAY less on it then i do on a below parallel squat. Even with a relatively high box (had to use a bench which was slighlt above parallel) and a wide stance I stopped at 245 X5. Hell even when i did close stance, feet together box squats in the past I could handle upwards of 315 or so for 3 reps or so. Granted its been a few weeks since i had worked legs but still the drop off suprised me.
Is this normal? I thought you were supposed to be able to handle more weight on a box.