The 200 gr ELD X is rated for a 1-10 twist. I’m shooting the 178’s out of my Abolt 300 wsm. They group really nice for me 12 consecutive shots in a 1” group. 2975fps. Them are handloads, over RL17, can’t remember the powder charge. Tried them out to 500 yds with excellent results. Hoping to have a picture of an exit would the first week of November.