I was wondering if deer ever still grow there racks when they go hard horned?

I don't believe so, I think they grow while the velvet is on, but once it hardens, the growing stops.

all growing stops a few weeks before they shed velvet. the antler hardens, and the velvet is rubbed off. after that, no more antler growth occurs until the antlers are cast and the bucks begin growing new ones again.

slayer

The velvet is the lifeline of antler development, once it dies, the antlers discontinue growing. So consequently, bucks without velvet and with hardened antlers are at their largest for that season.