This concept was found on an airsoft site some time ago but thought it was cool.

Below are mock-up images of an upper receiver that enables any M16 rifle derivative to be converted into an automatic barrel change support weapon that reduces barrel overheating/erosion during hours of sustained fire. It uses an operation based on the Webley Fosbery Automatic Revolver to rotate the barrels for each shot. Not sure about its ROF but possible it accelerates the longer its fired as it may build centrifugal force. As for the ammo supply, C-MAG 100 round drums or a ceiner belt feed would be preferable.

I thought this could be a cheaper, less complicated alternative for the M134 Minigun but for land use.

The idea is quite fun of course, but i'm somewhat sure that it'd suffer from what most assault rifles turned to support weapon duty, it just won't hold up to the increased amount of firing.

For example the Israelis tried with their Galil, they didn't last well, even though they had beefed up receivers.

Unless something radical will happen with materials, thus making it more sturdy but with the same bulk then i just can't see the concept gain any wide acceptance.

But to own one for plug'n'play... wow..

The weight of the barrels reciprocating and the power of the recoil are all focused on one tiny piece of metal, that is the land that runs in the groove on the "Fosbery" cylinder.

The Fosbery was prone to catastrophic malfunction in the trenches, when the groove got filled with dirt.

Would you want your assault rifle to rely on such a small margin of error.

Fun toy, fun idea, need to work on the system.

BTW - I love the Fosbery, but it's not a combat handgun, a very accurate revolver, but not a combat handgun.