Hi, new to the forums here. I'm looking to build a rifle for home defense and leisure shooting. I know that 5.56 immediately comes to mind but I used that round in combat, it's crap as far as I'm concerned. I'd rather go with 7.62x39 as it has more stopping power. I was debating on 6.8 SPC but at 24 bucks for a 20 box, it's not very economical. I'd like to go out to the range and sit down for several hours and just shoot without wasting 60+ bucks on ammo. Now, I know you guys are all gun nuts so if I say something dumb, please be kind. I know little about the actual components of the weapon beyond what was needed to break down to clean and service. That being said, I'd like a 7.62 (or if you can convince me, 6.8 or 5.56) with a free floating barrel. I'd like the for the railsystem to extend as far towards the front sight post as possible as I intend to put railcovers on and paint them OD Green (Going for a nice look, see). The reason I'm here, asking for help is because I have no idea what is compatible with what, a majority of this nomenclature is lost on me. My target cost is roughly 900 USD. Is there anything else you guys need to know about what I'd like?