they list a 6.5Creedmoor "fat neck", what is that and what would the advantage be for small rifle primer over large?

Per website:

The Peterson Cartridge' 6.5 Creedmoor Fat-Neck™ has been developed for competition shooters who prefer to turn down the neck walls of their casings. With a neck wall thickness between .0155 - .0160, the Fat-Neck™ provides 6.5 Creedmoor shooters with enough material to turn down and reach exact fit for the chamber of their gun.

Link to website

small rifle primer in a standard cartridge (308, 6.5 CM, etc) will get more reloads on the brass, and it will handle higher pressures than a large rifle primer.

thanks Chad, another day not wasted, I learned supin!

Can anyone vouch for the quality of Peterson? At it's price point, I'd expect it to be up there with Lapua.