I believe it is 1:28 which in my barrel is a total of only one revolution unfortunetly as it doesn't stabilize slugs well...I found a 30in. .30cal barrel online that I might pick up eventually for the test valve im building it's only $40 and the twist rate is 1:10...and I know that someone is gonna ask so ill just tell...im going to be using reloading bullets for ammo and a bolt action if I get the .30 barrel