I can recommend the "Springbreak" from Andrews Custom Leather. I have one in chocolate brown with two speed strip pouches for a 4 inch model 66 and really like it. It's a vertical clam-shell design and the spring tension holds the gun very firmly in place. He uses a soft and pliable leather for the shoulder and back straps, which makes the rig very comfortable. I stopped by his old shop before he relocated to St. Augustine to drop off a couple knives for custom sheaths to attach to the right-hand side of the rig and got a tour of the shop while I was there. His sons help some, but he pretty much does all the work himself. Expect to wait at least half a year and pay a pretty penny, but the end result will be worth the wait and cost. He's got some videos up on Youtube, in particular one featuring the horizontal "Monarch" version of the shoulder holster which will give you an idea of the design and the quality of his work.