This prototype was shown (along with some videos of it being fired) at the 2004 Shot show. If Paul Bunyan actually existed, this would make a great handgun for him.
You don't want to be within 5 yards to either side of this beast when it is fired, as a lot of powder will be burning past the short barrel.
The influence of fictitious gun designs in Hollywood movies and video games on the design is obvious.
At that time, Triple Action, LLC of Logan, Utah was looking for a manufacturer to license to produce it for sale. (Actually, the company was really promoting its recoil reduction system.) The designer is Janos Lakatos.
Will production be announced at this year's 2006 Shot Show, or will this go the way of an interesting design exercise? We'll see in a dozen days. [Answer: No. It was never seen again, and the company no longer exists. Wonder who has the prototype?]
For an image of swing-down breech lock, and some diagonal images, click on the continuation.
The Thunder .50 has a massive (as it should be), swing-down breechlock:
For an earlier .50 BMG handgun design, some of which were actually built, see this earlier A-C-E post on Bob Stewart's Maadi-Griffin handgun. Given the situation, you're not likely to get your hands on one of those, if you don't have it already.