I'm looking at purchasing a new Remington R-15 VTR 22" barrel Semi-auto. The Box is marked .223 but the receiver is stamped "Multi". Can I shoot both .223 and 5.56 in this gun? I would prefer to buy a gun that is capable of safely firing both calibers. The Remington website lists .223 as it's caliber, but I have had some well versed gun sellers say that 5.56 can also be used in this gun. The gun is selling for what I think is a good deal at $699. There is also a DPMS "Sweet 16" AR-15 for $819. It is clearly stamped .223 & 5.56. If I knew the R-15 could shoot both I would buy it as I already own a matching camo Nikon Predator 4x12 scope, and it's $100 cheaper. I wish the manufacturer's websites would clearer as to what their products are capable of shooting. The DPMS website also only lists .223 as it's ammo for most of their hunting/target guns, but when you look at the firearms they are stamped for both, frustrating!