I've been messing around squatting in briefs the past few weeks to try to get back under some heavy weight. This will probably be my last week in them because my form changes a lot from being a close stance raw squatter to box squatting wider stance in briefs.
Box Squat - Metal Pro Briefs
bar x10
135x5
225x5
315x3
365x2
briefs on
405x1
455x1
495x1
545x1
585x1
645x1
By far the hardest part for me (when it gets heavy) is unracking the weight. I feel way more comfortable with my raw close stance unracking the weight. Other than that, I felt pretty well. Like I said, I may squat one more week in briefs, then.... back to raw.
Accessory work
3x5 pause squat at 365lbs
50 per leg Single leg leg extensions.