Howdy!
I just got done with my search for a period correct pocket knife (1860s-1880s). I had carried a Case two blade trapper for a number of years at shoots, then found out they really were a 1930s style put out by Case. Then I went on a hunt and came up either a Barlow style or a Navaja. The only Navajas I could find several months ago were made by Muela, and I didn't care for their quality/construction on the ones in their affordable price range. (I've since come across much better.) I then turned to Barlow style knives and was able to pick up a Russell grandaddy, single blade, spear point, high carbon and a regular size double blade high carbon model; both Solingen made, both discontinued, but still out there. Both fit in my vest pocket. (I also purchased a few Case barlows, grandaddy and regular; very good quality, stainless steel blades, USA made, for non-cas use.)
I've done more searching since and figure English Jacks (large and small) would also fit the bill. Two other USA manufacturing companies I've purchased from are Schatt and Morgan (a high end division of Queen Cutlery); (their recent grandaddy barlow in ATS 34 steel is a real humdinger! They also did a neat spear point single blade regular barlow as well), and Great Eastern Cutlery, their Tidioute division, also very high quality, although their knives do seem to run just a tad smaller length wise, but wider than usual, and tend to 1095 high carbon (tool) steel. Their 'bullet-end' or 'swell-end' two blade English jack is turning into a real winner for me!
Here are a few web sites to peruse:
For Barlows, English Jacks, etc look at:
http://www.caseknifeoutlet.com/index.cfmhttp://www.collectorknives.net/index.htmlhttp://www.knivesshipfree.com/index.php?cPath=457http://www.allaboutpocketknives.com/knife_store/knifestore909-y.htmlhttp://www.cumberlandknifeworks.com/index.php?page=shop.browse&category_id=105&option=com_virtuemart&Itemid=28For box loads of Navaja style knives (look at pocket and folding knives sections):
http://www.worldknives.com/index.php(The Muela Navaja listed here looks vastly better than the one on amazon!)
Hope this helps!