I was just surfing Cabela's website and saw a kit to make an ar15 a .50 cal rifle.  Is this old news?  I'm a complete newbie, but haven't seen any mention of it on this site in the past month or so...  What are everyones thoughts on .50 Cal conversion kit?  Below is the info from Cabela's website ad:

"Alexander Arms .50 Beowulf Entry Kit
Give your Colt AR-15 the power and performance of a .50-caliber cartridge without sacrificing its easy-handling, semi-automatic characteristics. Alexander Arms' Entry Kit comes complete with all the components required to permit your AR-15 to shoot the new .50 Beowulf, creating a rifle ideal for everything from big-game hunting to target shooting to home defense and other tactical uses. Initial tests have shown this round to be extremely accurate, consistently producing groups measuring smaller than 1" at 100 yards. Recoil is also very manageable, much like shooting a 20-gauge shotgun. Kit comes complete with flat top receiver with Picatinny rail, mid-length hand guard, 16" barrel with Picatinny front sight block and seven-round magazine. Lower receiver not included. "

I've seen it too. The only thing I have a problem with is ammo.  Its the same with all of the other odd calibers .454 .480 one company makes it, and the cost of shooting it, isn't cheap.