The big advantage of the Blaser action is its strength. It is based on a patent obtained by Franz Jaeger in 1906 and is probably the most powerful of all hinged actions, since the lockup is entirely independent of the hinge pins and underlugs.

The lockup occurs when a moveable breech block containing the firing pins, is cammed into a recess in the barrel extension, the way a falling block single shot locks in a recess in the action, except in this case the recess is above the block and the recess is cammed down onto the block as the action is closed.

Locked up in this way, all strain is removed from the frame of the action, the same way the lock up of an AR-15 rifle is achieved through a mating of the rotating bolt head with the barrel extension. The alloy "upper" just houses the parts and plays no role in containing the pressure generated by the cartridge as it is fired.

An action like the Blaser will never "shoot loose" because there is no strain on the parts which are stressed in any other system. The action does not transmit any of the force of the powder combustion either to the face of the action or to the hinge pin and no action bolt is needed to lock the underlugs.

Merkel, incidentally, uses the same system in their B3 double rifles.