I once had a gun built by Stevens on the 315 action. As John said they have inline strikers rather than swinging hammers Also notice the pin placement through the frame. The forward pin is the cocking lever pivot & also the hammer pivot on the 530/311 types. The rear pin is the sear pivot & is lower than the front pin on the 530/311 while higher on the 315 types. There is o0f course no Pivot for the inline striker on the 315 actions.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra