The bevel on the lockplate really doesn't prevent the splitting. What it does is allows for a tighter fit when inletting. I have inletted sidelocks myself, and understand the reason for the bevel. Meticulous inletting is a joy, but a bit of clearance may be called for at times. This is a pic of an inlet I did. I beveled the edges of the lockplate on it.
The issue is that a sidelock's overall shape is that of a wedge, on the rear. Recoil wants to force that wedge into the mating shape of the wood inlet. If the head of the stock gives any at all, or if the hand pin/tang screw is not fully tight, movement begins to force that wedge into the wood of the inlet, forcing the upper and lower halves of the inlet apart. Thus, a crack begins. Sometime only at the rear of the lockplate, sometimes at the rear end of the tang.
Your guns may have much more mating surface at the head of the stock than a Smith, Doug. It would be very hard for them to have less. They are very nice guns.
SRH
