I suppose there are any number of holsters which you could cut down in that fashion, but I would suggest a HEAVY leather holster with a wide and firmly stitched belt loop. I suppose you could get one that would cover a 4" gun and make it work for the other barrel lengths. Buy the time you buy a high quality leather holster and cut it, you could probably buy 4 nylon holsters for the same money that might serve you better. I do not like to carry barrels that protrude from the holster in the field because of the danger of scratching the finish on the barrel or inadvertantly poking the barrel into dirt, tree bark, damaging the crown on the barrel, etc..
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Roll Tide