I am a complete AR newbie. I shot one once, about 20 rounds and it was great and easy to shoot. All of my military, LEO, and or shooting friends claim "I have to have one". lol So I just bought a used BUSHMASTER XM15E2S. It has only had 100 rnds shot through it and not a single scratch on it. I got it for $700 which I do not think is bad. It has a traditional solid stock which I like and standard AR sights and no rails. So my plan is to add a quad rail and 200 lumen fore grip flashlight. Probably a 1 point sling and be good to go. This will primarily be a fun target shooting rifle while being able to say I have one. I don't plan on any lengthy battles, zombies are always a concern . It will probably be taken over by my 16 yr old [unless I go to the range by myself] who for some reason is a complete natural shooting an AR. So used with only 100 rnds through it, I do not consider it being broken in. So Black Gun guys and gals, what can I expect? Any advice, opinions or suggestions would be greatly appreciated. It states .223 or 5.56 so ammo recomendations and concerns as well as magazine pros and cons would be GREATLY appreciated. Thank you very much!!