It's probably a 1:8 twist, but you'll have to measure to be sure. There are a ton of videos on how to measure a twist on You Tube, go there and watch one. It's easier to send you there the trying to type it out. Because it is button rifled it may not be exactly 1:8 but could be within .25-.5" either way. As long as it's faster than 1:9 you shouldn't have any issues with the majority of bullets.