I'd vote for the H&R, however, I've never shot the 512. I had a bolt action Mossberg 695 slug gun. It had ejection issues. I looked @ the 512 and read a little on the web about ejection issues as well. The H&R 20 or 12 is a no brainer, cheaper as well. I have the 20 with a Leupold VX-II 3-9x40 on mine. Let me tell you it shoots wonderfully. I use Remington Accu-Tips in mine. I'd recommend the Leupold glass as it's outstandingly clear and will absolutely stand the test of time. Always get out your extra pennies for good glass.