When I was quite young, I saw this picture in one of my dad's gun books:

This was in
The Muzzle-Loading Cap Lock Rifle, by Ned Roberts. That was a long time ago, but the image stayed in my head, and I still have the book, which is the third (1947) edition, 1952 printing.
I took a closer look at the picture recently. At first glance, it's just a half-stocked Hawken. However, this one is different. The 28" barrel (from the photo caption) is shorter than most. A lot of these rifles were cut down, but Bob Woodfill wrote an article about short-barreled Hawkens that were purpose-built that way. This was in the April 2018 issue of
Muzzle Blasts, I believe, and it was reprinted as a chapter in Bob's book. These short Hawkens are not common, but a few are out there, and a couple of them have only one ramrod pipe on the rib, like this one.
Shiff's rifle also has only one barrel key, which really is unusual. The rear sight looks atypical to me, as it is not leaning back and it appears very low. The photo also appears to show a drum and nipple arrangement rather than a patent breech. I've seen this on a couple of Hawken-marked rifles that appeared to be spurious, but this one, despite these atypical features, has the Hawken "look," to me.
The triggerguard seems to have very shallow bow, and the buttplate looks like it was forged out of rather thin stock, rather than cast. The inside corner, where the return joins the body of the buttplate, looks square rather than radiused. Bearing in mind that this rifle is marked
S. HAWKEN ST. LOUIS,and not J&S, it must be post 1849, which is when Jacob died in the cholera epidemic. I thought by that time Sam was using cast buttplates.
One other thing is that the caption says this rifle is .45 caliber. I know the Hawken shop produced some smaller caliber rifles for emigrants and the local trade, but this rifle weighs over ten pounds. I ran some numbers with a barrel weight calculator and calculated that a 1.125" barrel of .45 caliber, 28" long, would weigh a little over seven pounds, which would probably be in the ballpark.
Generally speaking, guns owned by famous people are more highly regarded than those carried by the hoi polloi. While "Shiff the Gunman" is hardly as well-known as some other Hawken owners like Carson, Bridger, "Liver Eating Johnson," and so forth, he was pretty well known among gun traders for a number of years.
There is some information about him "out there," in print and on the web, but it is fragmented and sometimes contradictory. His name was either Carroll B. Shiff or Carl B. Shiffer, but he used the name "Shiff the Gunman" for his gun trading business. Depending on whom you believe, he was either born in July, 1855 in a covered wagon in Montana Territory, or in 1878 in Waterloo, Iowa. Those who report the earlier date indicate Shiff was a typical westerner, doing some trading, trapping, hunting, cowboying, etc. before moving to the vicinity of Woodstock, New Hampshire. The exact date that he established his business may not be clear, but I understand he was in New Hampshire by 1902, and lived there as sort of a recluse until his death in August, 1952, at the age of either 97 or about 74. Ned Roberts apparently knew him, and espoused the earlier birthdate. Roberts himself was born in 1866, and he probably would have known if a man was younger than himself. The November 1952 issue of
Muzzle Blasts, published three months after Shiff's death, ran his photo on the cover, with a memorial article by Major Hugh Smiley:

Major Smiley knew Shiff, but paraphrased a lot of what Ned Roberts had already written along with some additional information provided by himself. Ned Roberts thought enough of Shiff to put his photograph (with that same Hawken rifle on his lap) and a short bio in the preface of his book:

That photograph and write-up by Ned Roberts was evidently in the first edition of
The Muzzle-Loading Cap Lock Rifle, which was published in 1940. Shiff would have been 85 then, if he had indeed been born in 1855.
Stan Holz wrote a biographical article about Shiff, published in the October 2012 issue of
The Outdoor Gazette. Mr. Holz investigated all of the sources he could find, including archived materials, and stated positively that Shiff was born in 1878, in Iowa.
A lot more could be written about Shiff in this post, but I wanted to keep it as brief as I could, at least for now.
In any event, what we have here is a pretty good old photograph of a rather unusual original Hawken rifle, which was owned at one time by a colorful and eccentric individual who was well known and well regarded in the shooting world. I wanted to throw this out there for you folks to look over and comment on the rifle or on Shiff the Gunman. I was also wondering if anyone has any idea regarding this rifle's current whereabouts. It would be great to have it properly examined and written up by one of our resident experts.
Best regards,
Notchy Bob