Commenting here as I can't comment on the blog. Interestingly the same thing occurred when I tried commenting on one of your calcs over at vsbattles. Something about login session problems.
Anyways, we've used arm movement speed in the past, like with Machamp I'd assume the same logic is workable here. Plus I kinda need to since he had to move his arm after turning, otherwise he'd have a bolt in his face.
I'm using crossbow bolts, not bullets. The fastest bolts can travel at velocities of 440 fps according to google.