Back in the sixties "BULLPUPING" was very popular and Styer made a bullpup magazine rifle that was a good design with the magazine in the buttstock. The rifle was no longer than a submachinegun, but sported a 22" barrel.

The double pictured here is just about as ugly as I've ever seen, but in a tight crawl-in to sort out a cat in in the rock cravases of a kopge it may have some merit. Another application is a survival rifle for bush pilots comes to mind. The rifle could be chambered for anything up to 458 Win mag, but I'd leave the barrels exposed from the trigger guard forward!

Not my cup of tea, but still it has some aplications that make sense, IMO!