The best boxlock action is the Perazzi action used first on the DC1 SxS in the mid-60s, and still being used on the DC12 today. The unique action is based on the MX8 OU action but with a hook under each barrel, with locking bars that engage the action at the standing breech. Keep it clean and lubed and it will last forever. The twin barrel hooks make so much sense. Recoil comes straight back minimizing off center torque. I dont know why no one thought of it before Mr Perazzi.