They're not designed specifically for firearms, but you might be interested in some of the Tom Bihn bags (
http://www.tombihn.com ). I just have a laptop bag with a removable braincell (for laptop protection), and it's been a great, versatile everyday bag. I went with the ordinary black one, but I picked the red/orange interior (cayenne). I think the larger bags with compartment options may be closer to what you need.
Besides that, there are the Ape Case (
http://www.apecase.com ) (yellow interiors) and Lowepro (
http://www.lowepro.com/ ) camera bags. I have a Lowepro that's been great, but I haven't used it as a range bag. Still, a lot of movable compartments and made to keep sensitive things safe.
Finally, for something completely different, back when I couldn't justify the expense of a really nice bag and was a little concerned about its attracting attention--especially with camera gear--I used a diaper bag. They tend to be waterproof, have customizable compartments and, most of all, are far less likely to be stolen.