I looked for over a year for a RPR 556. they got a slow sales start, then picked up as people figured out what they were good for. At just that point ruger discontinue them. found one finally, paid a premium ( which should be expected). My use is as a varmint rifle. I rebarrelled it in 204 ruger, use it as a varmint rifle. Its a killer for that, as its ergonomics allow you to spot your own shots.
others use it as a practice gun. 223 is cheap, the barrel life is double to triple what a prs caliber gets. And the mags that come with it are long for 223, allowing you to seat bullets out as neck wears. many do crater primers, but the fix is readilly available and costs less 100$. My 2 cents, id buy this one if i hadnt found one