To say that Webley A & WC, and PHV-1 actions both feature screw grip fastening is incorrect.

Both types of third bite are attempting to contain the same force during firing but they actually achieve this in two TOTALLY different ways.

The A & WC system delivers a tension force along the shaft of the screw. (top lever spindle) This is a screw grip system.

The PHV-1 system delivers a compression force acting on the top lever extension which is supported by the top of the action frame. This is really a wedge grip system.

So not only do they work in different ways, they actually work in opposite ways.

The PHV-1 does not use a screw fastening system for the third bite so suggesting that it is a "screw grip" is wrong.

Examine the two different types, look at how the load is transmitted from the barrel extension to the other components relating to the third bite and you will see there is a huge difference.