Cliff, that ridge for the frog to catch on is a piece of cake. It's nothing more than a 3/8" wide strip of 8 ounce cowhide cut long enough to go all the way around the scabbard. I skive both ends of the strip down thin and have them meet dead center in the back, where the seam line is going to be. The strip is glued in place with Barge cement, and when the outer covering is stitched on the strip forms that ridge that you see. Like I said, piece of cake. "As issued" khuk scabbards don't need the strip because of the flared effect created by the housing for the karda and chakma. Removing the chape and karda/chakma housing (basically just a strip of wood, some nails, and a couple of leather loops), makes for a "high speed, low drag" scabbard. You will need to modify the frog, even with the new ridge in place, that's a piece of cake too. Just use a good hole punch of the correct size to form a new row of holes, adjacent to and inboard of the existing ones (eyeball it good first with the frog on the modified scabbard to guage where the new rows of holes should go). Trim off the leather with the old holes using a sharp pair of good scissors. Re-lace and install. Good stuff, dirty deeds done dirt cheap, wore my 12" AK all day long and nobody even knew I had it!
Sarge