Those are standard pinned handles/solid bolsters with a through-and-through pivot pin. Very "typical" slipjoint construction. Those two knives were built well before the shell handle patents were applied for, I believe. The "arched" Colonial stamps were dated from 1926-1938 by a couple online sources - YMMV of course! I "borrowed" a close-up pic of the stamp from another forum:
Those big hunters are absolute stunners, David! Fantastic finds! I am green with envy!