At last, finally got this image to take. I found this in "American Primitive Knives 1770-1870", Gordon B. Minnis, 1983,
As noted, it seems the gadrooned grip was something used c.1850 as far as on Bowie's, in this case hardwood.
This gives some idea of the likely inspiration for your example. I have not yet gotten to Flayderman ("The Bowie Knife", 2004) which is of course the most comprehensive reference on these.
Hopefully there are others out there interested in Bowie's.
The size of this thing is remarkable, 12" blade????!!!!
Very 'Crocodile Dundee'.....now THATS a knife
Couldnt resist adding this perspective