I'd set my eye relief the way most people probably do, getting everything lined up nice and easy and calling it good. A competition shooter watched me do it for about thirty seconds before pointing out that I'd basically optimized for the one position I'd never actually use the gun from.
He had me set it instead for my natural, dynamic head position, the one I actually land in under movement and it turned out to be a completely different distance than what I'd settled on at the bench. The difference showed up immediately, when I brought the gun up fast from a ready position, the sight picture was just there, instantly, instead of needing that little adjustment I'd gotten so used to that I stopped noticing it. Eye relief apparently needs to be set for how you actually shoot not how you sit there comfortably setting it up.
He had me set it instead for my natural, dynamic head position, the one I actually land in under movement and it turned out to be a completely different distance than what I'd settled on at the bench. The difference showed up immediately, when I brought the gun up fast from a ready position, the sight picture was just there, instantly, instead of needing that little adjustment I'd gotten so used to that I stopped noticing it. Eye relief apparently needs to be set for how you actually shoot not how you sit there comfortably setting it up.