No twist rates recommendations on the box but they were designed specifically the 35 Rem. Most 35 Rems are 1:16" twist. I believe 1:20" twists will be fine with enough speed. I wouldn't want to push them any slower than 1800fps mv so that at least a 1500fps impact velocity can be maintained. My barrel is a 18.75" twist and the bullets are stable at my speeds in the short distances I've shot them so far.
