If you are looking for a magazine carrier for Saiga 12 magazines, check out Black Rhino Concealment. They recently made a kydex belt mounted mag carrier that could be a great option for 3 gunners who compete with the Saiga 12.
This is the kind of thing that you will likely never be able to walk into a store and buy off the shelf. It’s slightly offbeat projects like this that make me glad small, quality kydex benders exist. Can you imagine trying to find a solution like this before there was a kydex maker in seemingly every city to serve every niche? We have it pretty good.