Wrong attitude about 300, Danny. You have 300 in you. Rest sufficiently between sets.
Get your torso more rigid. Lift the chest up hard before you begin each rep and keep it that way. Don't drive the chest, just lift the damn thing. I'd still like your knees to get to their spot sooner. Can't tell from this angle whether they're sufficiently shoved out.
Overall, these look much better than some of your previous videos. You're making good progress. Don't let your brain limit you. 300 will fall to you. 300 WILL FALL.