I have wondered about those St. Louis "California" rifles, and would enjoy reading a discussion. I also went so far as to purchase a copy of Shelton's
California Gunsmiths 1846-1900. I've found a couple of brief references in other places, including a past issue of
Wild West magazine (sorry.. I don't have the citation handy). It is my impression that these were rifles built for emigrants and hunters headed for California some years after the "Mountain Man Era." There was plenty of big game in the Golden State in those days, including numbers gigantic California grizzlies. These tended to be big-bore rifles, I believe.
Meanwhile, the "Dimmick" style triggerguard appears to be a very common, if not predominant style on the rifles made
in California. From the pictures I have seen and references I have found, I would venture to say these later California rifles had slightly shorter barrels than the earlier "plains" rifles, and were typically half-stocks. If you Google "percussion California rifle" and look at the images, you might find a few surprises.
Finally, and maybe veering off a little, Henry Leman also made a lot of rifles for the California trade (see
ASAC Bulletin #51, p. 51/16). There is a nice photo of a Leman California "Bear Rifle" in Caravaglia and Worman's
Firearms of the American West. It looks like a beefed-up, short barreled fullstock "Indian rifle," except it reportedly has
Bear Rifle engraved on the top barrel flat.
Back to the original post, I agree that there is a clear similarity between the Hawken that is pictured and the "Hawken" offered by T/C. The devil is truly in the details, but superficially, they are similar. One final point to be made is that I don't know of anyone who has made a serious attempt to duplicate the Hawken bore. John Bergmann built a beautiful Hawken style fullstock for me a while back, and we did the best we could (thanks to Bobby Hoyt) to replicate a Hawken barrel, with seven grooves and a tapered bore to simulate the "choke" that the Hawkens were known to have put in their barrels. This one is .54 caliber. Unfortunately, I haven't had a chance to get it out and shoot it yet, but I sure am looking forward to it.
Meanwhile, the true definition of a St. Louis "California rifle" continues to elude us.
Best regards,
Notchy Bob