Nute burn on mature ladies? pic

This Blackjack is 35 days into flowering on 400w HPS. Used FF Grow big through 2 month veg. and It has been getting half strength FF tiger bloom and m.o.a.b. for the last two weeks. Usually after every two waterings, and it's ph balanced to 6.5.

Am i just pushing her too hard? or is it a deficiency of some other kind that I am not aware of?

Looks like nute burn to me. I would flush and lower the PH a bit and kick the feeding back on. You need to try and find the sweet ph spot where they can handle the most amount of nutes. Not a bad burn so I wouldn't trip.