Glock5857 wrote:
Is there any benefit in shooting 5.56 ammo over .223 or vice versa ?
From a practical standpoint for the casual shooter, it won't make a meaningful difference.
Now, as soon as I have written that someone is going to come along and say that:
* X Manufacturer's 5.56 delivers more velocity, or
* Y Manufacturer's 223 has softer recoil, or
* Z Manufacturer's 5.56 will wear out your barrel overnight.
And if you're shooting in competition this might matter, but if you're just out at the range with friends punching paper, I doubt you will notice the difference. And if you think you would, buy two brands of ammunition (same bullet weight) and have a friend mix them up and put them in the magazine and see if you can tell the difference. I bet you can't.
I should point out that the only time I shoot factory ammunition is the first box through a new gun. I do that so if there is a problem, the manufacturer (or their attorney if it is a real problem) can't blame my reloads. After that, everything going through any gun I own (or my father owns, or my sons own), other than rimfire, is something I assemble.
Buy on price.
But, I urge you to give preference to American manufacturers. After all, someone has to buy American products if any of us want to continue to have jobs. It's only a few cents more and the job you save may ultimately be your own.