I’m 6’2” and currently 270. I use grade 8 bolts and also have titanium bolts. I haven’t bent either yet. Keep your foot against the tree as said above. Also if you decide to use one of the unconventional bolt materials don’t space them out so far that you have to heave yourself up to the nest bolt. People don’t bend bolts trying to step up but the bounce and sudden surge to help them step up to the next one.