I'd like to shoot one. For the past 20 years, any double barrel handgun has quickly been shot down (cwhatIdidthere) as impractical, just a novelty toy. With a handgun, especially with larger calibers, I can see how you're basically just doubling your recoil, increasing weight, and accomplishing nothing special by adding a second barrel.
But with a .556 and in a rifle (with such manageable recoil to begin with), I'd say "why not?" Not an affirmative, not a "great", not an applause, just a "why not"?
If you look at it from a purely academic point of view, two holes for the price of one sounds like a great idea. If anything, it's the reality setting in of two bolts, two firing pins, and how it plays out when it malfunctions. Actually that creates another line of thought: If you get a failure to fire/feed in one side of the chamber, does the other chamber still fire? That could -in theory- be a great pick up in reliability.
