The rifle Dave B references is on page 364. It has a long breech tang held on by two wood screws, not bolts to the trigger plate. The hole in the front trigger plate finial is for a wood screw. Four of five "sporting rifles" in Gordon's book have the trigger plate held on with wood screws. The fifth one (page396) has a short breech tang with one wood screw. The guard is pinned to the stock front and rear. The one on page 392 has a short breech tang held with one wood screw. The trigger guard is screwed to the wood front and rear. The one on page 393 has a long breech tang with two wood screws. The trigger guard is held with a wood screw front and rear. The rifle on page 394 has a long breech tang held with two wood screws. Wood screws front and rear hold the trigger guard. The rifle on page 395 has a long breech tang held with two wood screws. The trigger guard is held with wood screws. None of these five rifles have a hooked breech. So, no, there is no pictured Hawken rifle with a screw that goes from the trigger plate into the bottom of the standing breech. It is unlikely that any were made that way.
The James Dunn rifle on page 365 has the breech tang held with wood screws. The trigger plate is held with a screw at rear and is pinned at the front.