I found a Galco design that uses a strip of leather the same thickness as the holster itself and stitched around the opening to do much the same thing. I supposed the width of the strip as well as the stitching provide the required tension to hold the opening in it's preferred position. I have been packing this holster around now for going on three years and it is holding up pretty well. Every other week for daily wear with the holster and magazine pouch is pretty comfortable and wearing them on my also home made 1 and 3/4 inch wide western styled belt.
You can see just how far around the strip of leather goes around the backside of the holster here.
On the off week that it resides in the gun safe my Ruger P-90, .45 ACP with a similar set up of twin magazine pouch and holster is what gets the nod. I will also admit to packing some older iron in the form of either my Ruger Blackhawks or Uberti Hombre in more homebrew leather on my days off when I am going out and about to the desert to shoot or hunt yodel dogs or other fun and games.
With the single actions instead of magazine pouches I go with cartridge loops around the belt.