Hi first of I really appreciate your opinions. I know a similar question has probably been asked but, I am kind of on a limited budget for this one. My question is if you had about 1200 to spend either new or used and wanted to buy a shooter that you could put a decent amount of rounds through, but still be able to really on it for protection if the Zombie apocalypse ever does happen. I am a complete newbie to this platform other than the S&W MP 15-22 that I love. It has a very inexpensive red dot that I really like. So I don't know if I need a flattop optics ready gun or it can go on a gun with a carry handle? I also was curios about gas piston or no gas piston. Any advise would be greatly appreciated. Thank you in Advance....Jason