Trust me, I get upset that it’s only 455 but the lift off the floor is hard for me as my upper body is so much weaker then my lower. Holding and pulling 500lbs vs lettin it rest on your back and pushing can make a big difference in a lift.
I have had over 600 on my back which I call “walkouts” just to get use to “feel” of the weight but I can’t even hold that much let alone pick it up off the floor because it slips out my fingers/hands. Any slipping weight out of hands is a sign you need grip work: fingers, forearms ect…
I know how to fix it which the protocol is extensive grip work but like Charlie said if I go down that road I’m starring to go outside the scope of training as a sprinter. Also if I develop my forearms to be thick I would say it’s just as bad as developing thick calf muscles.