I'm looking to put together a rifle for my 11yr old to hunt with next year, and leaning heavily towards either a .257 Roberts or 6.5x55. I like the prospect of using the 6.5x55, simply because I already have a rifle in the cartridge and another rifle in .260...so bullets aren't a problem. Factory 6.5x55 ammo is cheaper, especially the Prvi stuff, and seems like the 6.5x55 would be a tad bit more versatile.
I have nothing in .257, so it would mean buying dies, brass, bullets, etc. Any reason to go with the .257, other than the fact I really want one?
