question about pinion nut

My pinion nut gets stuck once the top of the nut meets the top of the thread of the pinion gear

I had tightened it with a racthet the more i went down the hard it was to turn and when i took off the nut there were indentations right where the nut got stuck this is what i guess is stopping it from going down, but is my pinion nut bad? or is it suppose to get tight like that?(i tired to turn in down on both new pinon and old pinion gear get stuck at same point)

wear the marks are on up above the metal is actually bent a little causing the bare metal to show, i think it might be the nut, but i had another one nut with the same exact problem.