What Doc hasn't mentioned but one of his pics hints at: the old thread is a BEAR to remove from old holsters (last one for me was a Heiser). The thread is linen from that era and quite strong still -- and has been trapped inside shrinking needle holes for up to a century. Hence the needle nose pliers he's using in one pic to pull the threads after the welt stitching has been slit apart. On a Threepersons holster, such as this one, the pistol grip enables an extraordinary amount of leverage against the welt at the open end and those old makers didn't stitch them with this in mind, as the rest of us did later beginning with Wally Wolfram.

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Red Nichols The Holstorian