I bought a Youth Remington 870 20ga. On the barrel it says 2 3/4" and 3" shells, on the receiver it just says Remington 870. It does not say Express Magnum. My question is, is it OK to shoot 3" magnum buckshot out of this gun? I'm going to keep it for home defense, I know this sounds dumb but I'm not a shotgun person. Is there a deference in 3in and 3in mag or are they one in the same? Thanks for all input.