I love my AC556 . I had a FNC Semi, thought about buying a sear, researched on installation, burst kits and finding parts. Gave up bought the AC and started having fun. I always wanted an M16 but for the 1/3 the money I got a fresh back from Ruger (new barrel, bolt, trigger pack, etc.) Stainless KAC-556. I looked at several RR AR15's but wasn't confident spending $10K. Some may be good guns but I knew the Ruger was built like a tank. The only downside was not being pistol caliber compatible. So, traded the FNC for a 9mm M10. If money wasn't an object yea I probably buy an M16. But the Ruger is a great gun, wouldn't trade it even for a RR AR15. At first I had an inferiority complex when shooting with others who had M16's but after dropping it into a SCAR stock the comments I got cured that. This baby will eat anything. My only wish is that Ruger would sell me the new 16" barrel or would install one. I talked to a Ruger trained LEO Armorer who stated the barrels are a bugger to time and bolt must be fitted.